diff --git a/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/test/utils/TestingUtilities.java b/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/test/utils/TestingUtilities.java
index 62999b83d..00bc0fb47 100644
--- a/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/test/utils/TestingUtilities.java
+++ b/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/test/utils/TestingUtilities.java
@@ -88,13 +88,10 @@ public class TestingUtilities {
     if (!Utilities.noString(s))
       return s;
     s = "C:\\work\\org.hl7.fhir\\build";
-    // FIXME: change this back
-	  s = "/Users/jamesagnew/git/fhir";
     if (new File(s).exists())
       return s;
     throw new Error("FHIR Home directory not configured");
   }
-  
 
   public static String content() throws IOException {
     if (contentpath != null)
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Manager.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Manager.java
index 7ec051cbc..1fde2d4fe 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Manager.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Manager.java
@@ -24,6 +24,9 @@ package org.hl7.fhir.r5.elementmodel;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.Map;
 
 import org.hl7.fhir.exceptions.DefinitionException;
 import org.hl7.fhir.exceptions.FHIRException;
@@ -34,23 +37,41 @@ import org.hl7.fhir.r5.model.StructureDefinition;
 
 public class Manager {
 
+  //TODO use EnumMap
   public enum FhirFormat { XML, JSON, TURTLE, TEXT, VBAR;
 
     public String getExtension() {
       switch (this) {
-      case JSON:
-        return "json";
-      case TURTLE:
-        return "ttl";
-      case XML:
-        return "xml";
-      case TEXT:
-        return "txt";
-      case VBAR:
-        return "hl7";
+        case JSON:
+          return "json";
+        case TURTLE:
+          return "ttl";
+        case XML:
+          return "xml";
+        case TEXT:
+          return "txt";
+        case VBAR:
+          return "hl7";
       }
       return null;
     }
+
+    public static FhirFormat getFhirFormat(String code) {
+      switch (code) {
+        case "json":
+          return JSON;
+        case "ttl":
+          return TURTLE;
+        case "xml":
+          return XML;
+        case "txt":
+          return TEXT;
+        case "hl7":
+          return VBAR;
+      }
+      return null;
+    }
+
   }
   
   public static Element parse(IWorkerContext context, InputStream source, FhirFormat inputFormat) throws FHIRFormatError, DefinitionException, IOException, FHIRException {
diff --git a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/validation/ValidationMessage.java b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/validation/ValidationMessage.java
index 862961b3e..f93bfdba4 100644
--- a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/validation/ValidationMessage.java
+++ b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/validation/ValidationMessage.java
@@ -51,6 +51,7 @@ package org.hl7.fhir.utilities.validation;
  */
 
 import java.util.Comparator;
+import java.util.EnumMap;
 
 import org.apache.commons.lang3.builder.ToStringBuilder;
 import org.apache.commons.lang3.builder.ToStringStyle;
diff --git a/org.hl7.fhir.validation/pom.xml b/org.hl7.fhir.validation/pom.xml
index e9e7c1ea8..9bf6bac5c 100644
--- a/org.hl7.fhir.validation/pom.xml
+++ b/org.hl7.fhir.validation/pom.xml
@@ -12,6 +12,10 @@
     <artifactId>org.hl7.fhir.validation</artifactId>
     <packaging>bundle</packaging>
 
+    <properties>
+        <micronaut.version>1.3.4</micronaut.version>
+    </properties>
+
     <dependencies>
 
         <!-- HAPI Dependencies -->
@@ -138,6 +142,48 @@
             <version>${validator_test_case_version}</version>
             <scope>test</scope>
         </dependency>
+
+        <dependency>
+            <groupId>io.javalin</groupId>
+            <artifactId>javalin</artifactId>
+            <version>3.8.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.28</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.10.3</version>
+        </dependency>
+        <dependency>
+            <groupId>org.thymeleaf</groupId>
+            <artifactId>thymeleaf</artifactId>
+            <version>3.0.9.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- End to end -->
+        <dependency>
+            <groupId>org.seleniumhq.selenium</groupId>
+            <artifactId>selenium-chrome-driver</artifactId>
+            <version>3.141.59</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.github.bonigarcia</groupId>
+            <artifactId>webdrivermanager</artifactId>
+            <version>3.6.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -151,5 +197,4 @@
             </plugin>
         </plugins>
     </build>
-
 </project>
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java
index 53237c8d0..0d76dfa8d 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java
@@ -1068,6 +1068,13 @@ public class ValidationEngine implements IValidatorResourceFetcher {
     return isBundle;
   }
 
+  public OperationOutcome validate(byte[] source, FhirFormat cntType, List<String> profiles) throws Exception {
+    List<ValidationMessage> messages = new ArrayList<ValidationMessage>();
+    InstanceValidator validator = getValidator();
+    validator.validate(null, messages, new ByteArrayInputStream(source), cntType, asSdList(profiles));
+    return messagesToOutcome(messages);
+  }
+
   public OperationOutcome validate(String location, byte[] source, FhirFormat cntType, List<String> profiles) throws Exception {
     List<ValidationMessage> messages = new ArrayList<ValidationMessage>();
     if (doNative) {
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/Validator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/Validator.java
index c98dbfdde..8abac8da5 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/Validator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/Validator.java
@@ -49,12 +49,17 @@ POSSIBILITY OF SUCH DAMAGE.
 */
 
 import java.io.File;
+import java.net.URI;
 
 import org.hl7.fhir.r5.model.ImplementationGuide;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.utilities.VersionUtilities;
-import org.hl7.fhir.validation.cli.*;
+import org.hl7.fhir.validation.cli.ValidatorGui;
+import org.hl7.fhir.validation.cli.services.ComparisonService;
+import org.hl7.fhir.validation.cli.services.ValidationService;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.hl7.fhir.validation.cli.utils.*;
 
 /**
  * A executable class that will validate one or more FHIR resources against
@@ -75,6 +80,8 @@ public class Validator {
     VALIDATION, TRANSFORM, NARRATIVE, SNAPSHOT, SCAN, CONVERT, FHIRPATH, VERSION
   }
 
+  private static CliContext cliContext;
+
   private static String getNamedParam(String[] args, String param) {
     boolean found = false;
     for (String a : args) {
@@ -91,7 +98,29 @@ public class Validator {
     return Long.toString(maxMemory / (1024 * 1024));
   }
 
+  private static CliContext getCliContext() {
+    if (cliContext == null) {
+      cliContext = new CliContext();
+    }
+    return cliContext;
+  }
+
+  private static void goToWebPage(String url) {
+    try {
+
+      URI uri= new URI(url);
+
+      java.awt.Desktop.getDesktop().browse(uri);
+      System.out.println("Web page opened in browser");
+
+    } catch (Exception e) {
+
+      e.printStackTrace();
+    }
+  }
+
   public static void main(String[] args) throws Exception {
+
     System.out.println("FHIR Validation tool " + VersionUtil.getVersionString());
     System.out.println("Detected Java version: " + System.getProperty("java.version") + " from " + System.getProperty("java.home") + " on " + System.getProperty("os.arch") + " (" + System.getProperty("sun.arch.data.model") + "bit). " + toMB(Runtime.getRuntime().maxMemory()) + "MB available");
     String proxy = getNamedParam(args, Params.PROXY);
@@ -101,7 +130,13 @@ public class Validator {
       System.setProperty("http.proxyPort", p[1]);
     }
 
-    if (Params.hasParam(args, Params.TEST)) {
+    if (Params.hasParam(args, Params.GUI)) {
+      cliContext = Params.loadCliContext(args);
+      String v = Common.getVersion(args);
+      String definitions = VersionUtilities.packageForVersion(v) + "#" + v;
+      ValidationEngine validationEngine = Common.getValidationEngine(v, definitions, cliContext.getTxLog());
+      ValidatorGui.start(cliContext, validationEngine, true);
+    } else if (Params.hasParam(args, Params.TEST)) {
       Common.runValidationEngineTests();
     } else if (args.length == 0 || Params.hasParam(args, Params.HELP) || Params.hasParam(args, "?") || Params.hasParam(args, "-?") || Params.hasParam(args, "/?")) {
       Display.displayHelpDetails();
@@ -115,30 +150,32 @@ public class Validator {
       else {
         // first, prepare the context
         String txLog = Params.getTerminologyServerLog(args);
-        ValidationEngine validator = Common.getValidationEngine(args, txLog);
+        String v = Common.getVersion(args);
+        String definitions = VersionUtilities.packageForVersion(v) + "#" + v;
+        ValidationEngine validator = Common.getValidationEngine(v, definitions, txLog);
         Params.checkIGFileReferences(args);
-        Comparison.doLeftRightComparison(args, dest, validator);
+        ComparisonService.doLeftRightComparison(args, dest, validator);
       }
     } else {
       Display.printCliArgumentsAndInfo(args);
-      CliContext cliContext = Params.loadCliContext(args);
+      cliContext = Params.loadCliContext(args);
 
       // Comment this out because definitions filename doesn't necessarily contain version (and many not even be 14 characters long).  Version gets spit out a couple of lines later after we've loaded the context
       String definitions = VersionUtilities.packageForVersion(cliContext.getSv()) + "#" + VersionUtilities.getCurrentVersion(cliContext.getSv());
-      ValidationEngine validator = ValidationUtils.getValidator(cliContext, definitions);
-
+      ValidationEngine validator = ValidationService.getValidator(cliContext, definitions);
       if (cliContext.getMode() == EngineMode.VERSION) {
-        ValidationUtils.transformVersion(cliContext, validator);
+
+        ValidationService.transformVersion(cliContext, validator);
       } else if (cliContext.getMode() == EngineMode.TRANSFORM) {
-        ValidationUtils.transform(cliContext, validator);
+        ValidationService.transform(cliContext, validator);
       } else if (cliContext.getMode() == EngineMode.NARRATIVE) {
-        ValidationUtils.generateNarrative(cliContext, validator);
+        ValidationService.generateNarrative(cliContext, validator);
       } else if (cliContext.getMode() == EngineMode.SNAPSHOT) {
-        ValidationUtils.generateSnapshot(cliContext, validator);
+        ValidationService.generateSnapshot(cliContext, validator);
       } else if (cliContext.getMode() == EngineMode.CONVERT) {
-        ValidationUtils.convertSources(cliContext, validator);
+        ValidationService.convertSources(cliContext, validator);
       } else if (cliContext.getMode() == EngineMode.FHIRPATH) {
-        ValidationUtils.evaluateFhirpath(cliContext, validator);
+        ValidationService.evaluateFhirpath(cliContext, validator);
       } else {
         if (definitions == null) {
           throw new Exception("Must provide a defn when doing validation");
@@ -150,9 +187,9 @@ public class Validator {
           }
         }
         if (cliContext.getMode() == EngineMode.SCAN) {
-          ValidationUtils.validateScan(cliContext, validator);
+          ValidationService.validateScan(cliContext, validator);
         } else {
-          ValidationUtils.validateSources(cliContext, validator);
+          ValidationService.validateSources(cliContext, validator);
         }
       }
     }
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/RestEndpoints.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/RestEndpoints.java
new file mode 100644
index 000000000..055515301
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/RestEndpoints.java
@@ -0,0 +1,29 @@
+package org.hl7.fhir.validation.cli;
+
+import io.javalin.Javalin;
+import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.controller.CliContextController;
+import org.hl7.fhir.validation.cli.controller.ValidationController;
+import org.hl7.fhir.validation.cli.controller.UIController;
+import org.hl7.fhir.validation.cli.model.CliContext;
+
+public class RestEndpoints {
+
+  public UIController myUIController;
+  public CliContextController myCliContextController;
+  public ValidationController myValidationController;
+
+  public void initRestEndpoints(Javalin app, CliContext cliContext, ValidationEngine validationEngine) {
+
+    myUIController = new UIController();
+    myCliContextController = new CliContextController(cliContext);
+    myValidationController = new ValidationController(validationEngine);
+
+    app.get("/home", myUIController.renderLandingPage);
+
+    app.get("/context", myCliContextController::handleGetCurrentCliContext);
+    app.post("/context", myCliContextController::handleSetCurrentCliContext);
+
+    app.post("/validate", myValidationController::handleValidationRequest);
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidatorGui.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidatorGui.java
new file mode 100644
index 000000000..3030d0e2e
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidatorGui.java
@@ -0,0 +1,60 @@
+package org.hl7.fhir.validation.cli;
+
+import io.javalin.Javalin;
+import org.hl7.fhir.utilities.VersionUtilities;
+import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.hl7.fhir.validation.cli.utils.Common;
+
+import java.awt.*;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+public class ValidatorGui {
+
+  private static final int GUI_FRONTEND_PORT = 8080;
+  private static final String PAGE_ADDRESS = "http://localhost:" + GUI_FRONTEND_PORT + "/home";
+  private static final String WEB_APP_FILE_LOCATION = "/public";
+  private static Javalin app;
+
+  private ValidatorGui(){}
+
+  /**
+   * N.B. this entry point, is only for testing. Please start from command line using the argument {@code -gui} for
+   * actual use.
+   */
+  public static void main(String[] args) throws Exception {
+    CliContext cliContext = new CliContext();
+    String v = Common.getVersion(args);
+    String definitions = VersionUtilities.packageForVersion(v) + "#" + v;
+    ValidationEngine validationEngine = Common.getValidationEngine(v, definitions, cliContext.getTxLog());
+    start(new CliContext(), validationEngine, false);
+  }
+
+  public static void start(CliContext currentContext, ValidationEngine validationEngine, boolean bootBrowser) {
+    app = Javalin.create();
+    new RestEndpoints().initRestEndpoints(app, currentContext, validationEngine);
+    app.config.addStaticFiles(WEB_APP_FILE_LOCATION);
+    app.start(GUI_FRONTEND_PORT);
+    if (bootBrowser) {
+      openBrowser();
+    }
+  }
+
+  public static void openBrowser() {
+    if (Desktop.isDesktopSupported() && Desktop.getDesktop().isSupported(Desktop.Action.BROWSE)) {
+      try {
+        Desktop.getDesktop().browse(new URI(PAGE_ADDRESS));
+      } catch (Exception e) {
+        System.out.println("Error opening web browser to validator GUI.\nYou can try to open the page manually at:: "
+          + PAGE_ADDRESS + "\nError:: " + e.getMessage());
+      }
+    }
+  }
+
+  public static void stop() {
+    app.stop();
+  }
+
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/CliContextController.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/CliContextController.java
new file mode 100644
index 000000000..afd3e4478
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/CliContextController.java
@@ -0,0 +1,30 @@
+package org.hl7.fhir.validation.cli.controller;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.javalin.http.Context;
+import org.apache.http.HttpStatus;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.jetbrains.annotations.NotNull;
+
+public class CliContextController {
+
+  private final String JSON_MIME_TYPE = "application/json";
+
+  private CliContext myCliContext;
+
+  public CliContextController(CliContext cliContext) {
+    this.myCliContext = cliContext;
+  }
+
+  public void handleGetCurrentCliContext(@NotNull Context ctx) throws JsonProcessingException {
+    ObjectMapper Obj = new ObjectMapper();
+    String jsonStr = Obj.writeValueAsString(myCliContext);
+    ctx.result(jsonStr).contentType(JSON_MIME_TYPE).status(HttpStatus.SC_OK);
+  }
+
+  public void handleSetCurrentCliContext(@NotNull Context ctx) {
+    myCliContext = ctx.bodyAsClass(CliContext.class);
+    ctx.status(HttpStatus.SC_OK);
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/UIController.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/UIController.java
new file mode 100644
index 000000000..fcb978335
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/UIController.java
@@ -0,0 +1,13 @@
+package org.hl7.fhir.validation.cli.controller;
+
+import io.javalin.http.Handler;
+
+public class UIController {
+
+  public UIController() {}
+
+  public Handler renderLandingPage = ctx -> {
+    ctx.render("/public/index.html");
+  };
+
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/ValidationController.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/ValidationController.java
new file mode 100644
index 000000000..48af31ccd
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/controller/ValidationController.java
@@ -0,0 +1,38 @@
+package org.hl7.fhir.validation.cli.controller;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.javalin.http.Context;
+import io.javalin.http.Handler;
+import org.apache.http.HttpStatus;
+import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.model.ValidationRequest;
+import org.hl7.fhir.validation.cli.model.ValidationResponse;
+import org.hl7.fhir.validation.cli.services.ValidationService;
+
+public class ValidationController {
+
+  private ValidationEngine myValidationEngine;
+
+  public ValidationController(ValidationEngine validationEngine) {
+    this.myValidationEngine = validationEngine;
+  }
+
+  public void handleValidationRequest(Context ctx) {
+    ValidationRequest request = ctx.bodyAsClass(ValidationRequest.class);
+    ValidationResponse response = null;
+    try {
+      response = ValidationService.validateSources(request, myValidationEngine);
+      ObjectMapper Obj = new ObjectMapper();
+      /*
+       * TODO
+       * Write file contents to temp files to pass to validator instead of creating our own endpoint.
+       * Create File => new temp file
+       * Use Option => DeleteOnShutdown
+       */
+      String jsonStr = Obj.writeValueAsString(response);
+      ctx.status(200).json(jsonStr);
+    } catch (Exception e) {
+      ctx.status(HttpStatus.SC_INTERNAL_SERVER_ERROR).result(e.getLocalizedMessage());
+    }
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/CliContext.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContext.java
similarity index 68%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/CliContext.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContext.java
index 13146ee8c..951628ffa 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/CliContext.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContext.java
@@ -1,6 +1,8 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.model;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
 import org.hl7.fhir.validation.Validator;
+import org.hl7.fhir.validation.cli.utils.SnomedVersion;
 
 import java.util.*;
 
@@ -9,46 +11,82 @@ import java.util.*;
  */
 public class CliContext {
 
-  private String map = null;
-  private List<String> igs = new ArrayList<String>();
-  private List<String> questionnaires = new ArrayList<String>();
-  private String txServer = "http://tx.fhir.org";
+  @JsonProperty("doNative")
   private boolean doNative = false;
+  @JsonProperty("anyExtensionsAllowed")
   private boolean anyExtensionsAllowed = true;
+  @JsonProperty("hintAboutNonMustSupport")
   private boolean hintAboutNonMustSupport = false;
+  @JsonProperty("recursive")
   private boolean recursive = false;
-  private Locale locale = null;
-  private List<String> profiles = new ArrayList<String>();
-  private Validator.EngineMode mode = Validator.EngineMode.VALIDATION;
-  private String output = null;
-  private Boolean canDoNative = null;
-  private List<String> sources = new ArrayList<String>();
-  private Map<String, String> locations = new HashMap<String, String>();
-  private String sv = "current";
-  private String txLog = null;
-  private String mapLog = null;
-  private String lang = null;
-  private String fhirpath = null;
-  private String snomedCT = SnomedVersion.INTL.getCode();
-  private String targetVer = null;
+  @JsonProperty("doDebug")
   private boolean doDebug = false;
-  private boolean noInternalCaching = false; // internal, for when debugging terminology validation
-  private boolean noExtensibleBindingMessages = false;
+  @JsonProperty("assumeValidRestReferences")
   private boolean assumeValidRestReferences = false;
+  @JsonProperty("canDoNative")
+  private boolean canDoNative = false;
+  @JsonProperty("noInternalCaching")
+  private boolean noInternalCaching = false; // internal, for when debugging terminology validation
+  @JsonProperty("noExtensibleBindingMessages")
+  private boolean noExtensibleBindingMessages = false;
 
+  @JsonProperty("map")
+  private String map = null;
+  @JsonProperty("output")
+  private String output = null;
+  @JsonProperty("txServer")
+  private String txServer = "http://tx.fhir.org";
+  @JsonProperty("sv")
+  private String sv = "current";
+  @JsonProperty("txLog")
+  private String txLog = null;
+  @JsonProperty("mapLog")
+  private String mapLog = null;
+  @JsonProperty("lang")
+  private String lang = null;
+  @JsonProperty("fhirpath")
+  private String fhirpath = null;
+  @JsonProperty("snomedCT")
+  private String snomedCT = SnomedVersion.INTL.getCode();
+  @JsonProperty("targetVer")
+  private String targetVer = null;
+
+  @JsonProperty("igs")
+  private List<String> igs = new ArrayList<String>();
+  @JsonProperty("questionnaires")
+  private List<String> questionnaires = new ArrayList<String>();
+  @JsonProperty("profiles")
+  private List<String> profiles = new ArrayList<String>();
+  @JsonProperty("sources")
+  private List<String> sources = new ArrayList<String>();
+
+  @JsonProperty("mode")
+  private Validator.EngineMode mode = Validator.EngineMode.VALIDATION;
+
+  @JsonProperty("locale")
+  private String locale = Locale.ENGLISH.getDisplayLanguage();
+
+  @JsonProperty("locations")
+  private Map<String, String> locations = new HashMap<String, String>();
+
+
+  @JsonProperty("map")
   public String getMap() {
     return map;
   }
 
+  @JsonProperty("map")
   public CliContext setMap(String map) {
     this.map = map;
     return this;
   }
 
+  @JsonProperty("igs")
   public List<String> getIgs() {
     return igs;
   }
 
+  @JsonProperty("igs")
   public CliContext setIgs(List<String> igs) {
     this.igs = igs;
     return this;
@@ -62,10 +100,12 @@ public class CliContext {
     return this;
   }
 
+  @JsonProperty("questionnaires")
   public List<String> getQuestionnaires() {
     return questionnaires;
   }
 
+  @JsonProperty("questionnaires")
   public CliContext setQuestionnaires(List<String> questionnaires) {
     this.questionnaires = questionnaires;
     return this;
@@ -79,64 +119,87 @@ public class CliContext {
     return this;
   }
 
+  @JsonProperty("txServer")
   public String getTxServer() {
     return txServer;
   }
 
+  @JsonProperty("txServer")
   public CliContext setTxServer(String txServer) {
     this.txServer = txServer;
     return this;
   }
 
+  @JsonProperty("doNative")
   public boolean isDoNative() {
     return doNative;
   }
 
+  @JsonProperty("doNative")
   public CliContext setDoNative(boolean doNative) {
     this.doNative = doNative;
     return this;
   }
 
+  @JsonProperty("anyExtensionsAllowed")
   public boolean isAnyExtensionsAllowed() {
     return anyExtensionsAllowed;
   }
 
+  @JsonProperty("anyExtensionsAllowed")
   public CliContext setAnyExtensionsAllowed(boolean anyExtensionsAllowed) {
     this.anyExtensionsAllowed = anyExtensionsAllowed;
     return this;
   }
 
+  @JsonProperty("hintAboutNonMustSupport")
   public boolean isHintAboutNonMustSupport() {
     return hintAboutNonMustSupport;
   }
 
+  @JsonProperty("hintAboutNonMustSupport")
   public CliContext setHintAboutNonMustSupport(boolean hintAboutNonMustSupport) {
     this.hintAboutNonMustSupport = hintAboutNonMustSupport;
     return this;
   }
 
+  @JsonProperty("recursive")
   public boolean isRecursive() {
     return recursive;
   }
 
+  @JsonProperty("recursive")
   public CliContext setRecursive(boolean recursive) {
     this.recursive = recursive;
     return this;
   }
 
-  public Locale getLocale() {
+  @JsonProperty("locale")
+  public String getLanguageCode() {
     return locale;
   }
 
-  public CliContext setLocale(Locale locale) {
-    this.locale = locale;
+  public Locale getLocale() {
+    return Locale.forLanguageTag(this.locale);
+  }
+
+  @JsonProperty("locale")
+  public CliContext setLocale(String languageString) {
+    this.locale = languageString;
     return this;
   }
 
+  public CliContext setLocale(Locale locale) {
+    this.locale = locale.getDisplayLanguage();
+    return this;
+  }
+
+  @JsonProperty("profiles")
   public List<String> getProfiles() {
     return profiles;
   }
 
+  @JsonProperty("profiles")
   public CliContext setProfiles(List<String> profiles) {
     this.profiles = profiles;
     return this;
@@ -150,37 +213,45 @@ public class CliContext {
     return this;
   }
 
+  @JsonProperty("mode")
   public Validator.EngineMode getMode() {
     return mode;
   }
 
+  @JsonProperty("mode")
   public CliContext setMode(Validator.EngineMode mode) {
     this.mode = mode;
     return this;
   }
 
+  @JsonProperty("output")
   public String getOutput() {
     return output;
   }
 
+  @JsonProperty("output")
   public CliContext setOutput(String output) {
     this.output = output;
     return this;
   }
 
-  public Boolean getCanDoNative() {
+  @JsonProperty("canDoNative")
+  public boolean getCanDoNative() {
     return canDoNative;
   }
 
-  public CliContext setCanDoNative(Boolean canDoNative) {
+  @JsonProperty("canDoNative")
+  public CliContext setCanDoNative(boolean canDoNative) {
     this.canDoNative = canDoNative;
     return this;
   }
 
+  @JsonProperty("sources")
   public List<String> getSources() {
     return sources;
   }
 
+  @JsonProperty("sources")
   public CliContext setSources(List<String> sources) {
     this.sources = sources;
     return this;
@@ -194,10 +265,12 @@ public class CliContext {
     return this;
   }
 
+  @JsonProperty("locations")
   public Map<String, String> getLocations() {
     return locations;
   }
 
+  @JsonProperty("locations")
   public CliContext setLocations(Map<String, String> locations) {
     this.locations = locations;
     return this;
@@ -208,104 +281,129 @@ public class CliContext {
     return this;
   }
 
+  @JsonProperty("sv")
   public String getSv() {
     return sv;
   }
 
+  @JsonProperty("sv")
   public CliContext setSv(String sv) {
     this.sv = sv;
     return this;
   }
 
+  @JsonProperty("txLog")
   public String getTxLog() {
     return txLog;
   }
 
+  @JsonProperty("txLog")
   public CliContext setTxLog(String txLog) {
     this.txLog = txLog;
     return this;
   }
 
+  @JsonProperty("mapLog")
   public String getMapLog() {
     return mapLog;
   }
 
+  @JsonProperty("mapLog")
   public CliContext setMapLog(String mapLog) {
     this.mapLog = mapLog;
     return this;
   }
 
+  @JsonProperty("lang")
   public String getLang() {
     return lang;
   }
 
+  @JsonProperty("lang")
   public CliContext setLang(String lang) {
     this.lang = lang;
     return this;
   }
 
+  @JsonProperty("fhirpath")
   public String getFhirpath() {
     return fhirpath;
   }
 
+  @JsonProperty("fhirpath")
   public CliContext setFhirpath(String fhirpath) {
     this.fhirpath = fhirpath;
     return this;
   }
 
-  public String getSnomedCT() {
+  public SnomedVersion getSnomedCT() {
+    return SnomedVersion.getFromCode(snomedCT);
+  }
+
+  @JsonProperty("snomedCT")
+  public String getSnomedCTCode() {
     return snomedCT;
   }
 
+  @JsonProperty("snomedCT")
   public CliContext setSnomedCT(String snomedCT) {
-    this.snomedCT = SnomedVersion.resolveSnomedCTCode(snomedCT);
+    this.snomedCT = snomedCT;
     return this;
   }
 
+  @JsonProperty("targetVer")
   public String getTargetVer() {
     return targetVer;
   }
 
+  @JsonProperty("targetVer")
   public CliContext setTargetVer(String targetVer) {
     this.targetVer = targetVer;
     return this;
   }
 
+  @JsonProperty("doDebug")
   public boolean isDoDebug() {
     return doDebug;
   }
 
+  @JsonProperty("doDebug")
   public CliContext setDoDebug(boolean doDebug) {
     this.doDebug = doDebug;
     return this;
   }
 
+  @JsonProperty("assumeValidRestReferences")
   public boolean isAssumeValidRestReferences() {
     return assumeValidRestReferences;
   }
 
+  @JsonProperty("assumeValidRestReferences")
   public CliContext setAssumeValidRestReferences(boolean assumeValidRestReferences) {
     this.assumeValidRestReferences = assumeValidRestReferences;
     return this;
   }
 
+  @JsonProperty("noInternalCaching")
   public boolean isNoInternalCaching() {
     return noInternalCaching;
   }
 
+  @JsonProperty("noInternalCaching")
   public CliContext setNoInternalCaching(boolean noInternalCaching) {
     this.noInternalCaching = noInternalCaching;
     return this;
   }
 
+  @JsonProperty("noExtensibleBindingMessages")
   public boolean isNoExtensibleBindingMessages() {
     return noExtensibleBindingMessages;
   }
 
+  @JsonProperty("noExtensibleBindingMessages")
   public CliContext setNoExtensibleBindingMessages(boolean noExtensibleBindingMessages) {
     this.noExtensibleBindingMessages = noExtensibleBindingMessages;
     return this;
   }
   
-  
 }
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContextTest.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContextTest.java
new file mode 100644
index 000000000..82466642c
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/CliContextTest.java
@@ -0,0 +1,80 @@
+package org.hl7.fhir.validation.cli.model;
+
+/**
+ * A POJO for storing the flags/values for the CLI validator.
+ */
+public class CliContextTest {
+
+  private boolean doNative = false;
+  private boolean anyExtensionsAllowed = true;
+  private boolean hintAboutNonMustSupport = false;
+  private boolean recursive = false;
+  private boolean doDebug = false;
+  private boolean assumeValidRestReferences = false;
+
+  public boolean isDoNative() {
+    return doNative;
+  }
+
+  public CliContextTest setDoNative(boolean doNative) {
+    this.doNative = doNative;
+    return this;
+  }
+
+  public boolean isAnyExtensionsAllowed() {
+    return anyExtensionsAllowed;
+  }
+
+  public CliContextTest setAnyExtensionsAllowed(boolean anyExtensionsAllowed) {
+    this.anyExtensionsAllowed = anyExtensionsAllowed;
+    return this;
+  }
+
+  public boolean isHintAboutNonMustSupport() {
+    return hintAboutNonMustSupport;
+  }
+
+  public CliContextTest setHintAboutNonMustSupport(boolean hintAboutNonMustSupport) {
+    this.hintAboutNonMustSupport = hintAboutNonMustSupport;
+    return this;
+  }
+
+  public boolean isRecursive() {
+    return recursive;
+  }
+
+  public CliContextTest setRecursive(boolean recursive) {
+    this.recursive = recursive;
+    return this;
+  }
+
+  public boolean isDoDebug() {
+    return doDebug;
+  }
+
+  public CliContextTest setDoDebug(boolean doDebug) {
+    this.doDebug = doDebug;
+    return this;
+  }
+
+  public boolean isAssumeValidRestReferences() {
+    return assumeValidRestReferences;
+  }
+
+  public CliContextTest setAssumeValidRestReferences(boolean assumeValidRestReferences) {
+    this.assumeValidRestReferences = assumeValidRestReferences;
+    return this;
+  }
+
+  @Override
+  public String toString() {
+    return "CliContext{" +
+      ", doNative=" + doNative +
+      ", anyExtensionsAllowed=" + anyExtensionsAllowed +
+      ", hintAboutNonMustSupport=" + hintAboutNonMustSupport +
+      ", recursive=" + recursive +
+      ", doDebug=" + doDebug +
+      ", assumeValidRestReferences=" + assumeValidRestReferences +
+      '}';
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/FileInfo.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/FileInfo.java
new file mode 100644
index 000000000..7a6999b14
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/FileInfo.java
@@ -0,0 +1,49 @@
+package org.hl7.fhir.validation.cli.model;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import org.hl7.fhir.r5.elementmodel.Manager;
+
+public class FileInfo {
+
+  @JsonProperty("fileName")
+  private String fileName;
+
+  @JsonProperty("fileContent")
+  private String fileContent;
+
+  @JsonProperty("fileType")
+  private String fileType;
+
+  @JsonProperty("fileName")
+  public String getFileName() {
+    return fileName;
+  }
+
+  @JsonProperty("fileName")
+  public FileInfo setFileName(String fileName) {
+    this.fileName = fileName;
+    return this;
+  }
+
+  @JsonProperty("fileContent")
+  public String getFileContent() {
+    return fileContent;
+  }
+
+  @JsonProperty("fileContent")
+  public FileInfo setFileContent(String fileContent) {
+    this.fileContent = fileContent;
+    return this;
+  }
+
+  @JsonProperty("fileType")
+  public Manager.FhirFormat getFileType() {
+    return Manager.FhirFormat.JSON;
+  }
+
+  @JsonProperty("fileType")
+  public FileInfo setFileType(String fileType) {
+    this.fileType = fileType;
+    return this;
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationIssue.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationIssue.java
new file mode 100644
index 000000000..a18f1a33e
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationIssue.java
@@ -0,0 +1,32 @@
+package org.hl7.fhir.validation.cli.model;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class ValidationIssue {
+  @JsonProperty("severity")
+  private String severity;
+  @JsonProperty("details")
+  private String details;
+
+  @JsonProperty("severity")
+  public String getSeverity() {
+    return severity;
+  }
+
+  @JsonProperty("severity")
+  public ValidationIssue setSeverity(String severity) {
+    this.severity = severity;
+    return this;
+  }
+
+  @JsonProperty("details")
+  public String getDetails() {
+    return details;
+  }
+
+  @JsonProperty("details")
+  public ValidationIssue setDetails(String details) {
+    this.details = details;
+    return this;
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationOutcome.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationOutcome.java
new file mode 100644
index 000000000..1510c806b
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationOutcome.java
@@ -0,0 +1,47 @@
+package org.hl7.fhir.validation.cli.model;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import org.hl7.fhir.r5.model.OperationOutcome;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ValidationOutcome {
+
+  @JsonProperty("fileInfo")
+  private FileInfo fileInfo;
+  @JsonProperty("issues")
+  private List<ValidationIssue> issues = new ArrayList<>();
+
+  @JsonProperty("fileInfo")
+  public FileInfo getFileInfo() {
+    return fileInfo;
+  }
+
+  @JsonProperty("fileInfo")
+  public ValidationOutcome setFileInfo(FileInfo fileInfo) {
+    this.fileInfo = fileInfo;
+    return this;
+  }
+
+  @JsonProperty("issues")
+  public List<ValidationIssue> getIssues() {
+    return issues;
+  }
+
+  @JsonProperty("issues")
+  public ValidationOutcome setIssues(List<ValidationIssue> issues) {
+    this.issues = issues;
+    return this;
+  }
+
+  public ValidationOutcome addIssue(OperationOutcome.OperationOutcomeIssueComponent outcome) {
+    String text = outcome.getDetails().getText();
+    text.replace("\'", "\"");
+    issues.add(new ValidationIssue()
+      .setSeverity(outcome.getSeverity().getDisplay())
+      .setDetails(outcome.getDetails().getText()));
+    return this;
+  }
+
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationRequest.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationRequest.java
new file mode 100644
index 000000000..a515c5afa
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationRequest.java
@@ -0,0 +1,45 @@
+package org.hl7.fhir.validation.cli.model;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ValidationRequest {
+
+  @JsonProperty("cliContext")
+  private CliContext cliContext;
+
+  @JsonProperty("filesToValidate")
+  private List<FileInfo> filesToValidate = new ArrayList<>();
+
+  @JsonProperty("cliContext")
+  public CliContext getCliContext() {
+    return cliContext;
+  }
+
+  @JsonProperty("cliContext")
+  public ValidationRequest setCliContext(CliContext cliContext) {
+    this.cliContext = cliContext;
+    return this;
+  }
+
+  @JsonProperty("filesToValidate")
+  public List<FileInfo> getFilesToValidate() {
+    return filesToValidate;
+  }
+
+  @JsonProperty("filesToValidate")
+  public ValidationRequest setFilesToValidate(List<FileInfo> filesToValidate) {
+    this.filesToValidate = filesToValidate;
+    return this;
+  }
+
+  public String listSourceFiles() {
+    List<String> fileNames = new ArrayList<>();
+    for (FileInfo fp : filesToValidate) {
+      fileNames.add(fp.getFileName());
+    }
+    return String.join(", ", fileNames);
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationResponse.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationResponse.java
new file mode 100644
index 000000000..7c010916d
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationResponse.java
@@ -0,0 +1,33 @@
+package org.hl7.fhir.validation.cli.model;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ValidationResponse {
+
+  @JsonProperty("outcomes")
+  public List<ValidationOutcome> outcomes = new ArrayList<>();
+
+  @JsonProperty("outcomes")
+  public List<ValidationOutcome> getOutcomes() {
+    return outcomes;
+  }
+
+  @JsonProperty("outcomes")
+  public ValidationResponse setOutcomes(List<ValidationOutcome> outcomes) {
+    this.outcomes = outcomes;
+    return this;
+  }
+
+  public ValidationResponse addOutcome(ValidationOutcome outcome) {
+    if (outcomes == null) {
+      outcomes = new ArrayList<>();
+    }
+    outcomes.add(outcome);
+    return this;
+  }
+
+}
+
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Comparison.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
similarity index 91%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Comparison.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
index 2ae398529..5e584d339 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Comparison.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
@@ -1,4 +1,4 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.services;
 
 import org.hl7.fhir.r5.conformance.CapabilityStatementUtilities;
 import org.hl7.fhir.r5.conformance.ProfileComparer;
@@ -14,6 +14,7 @@ import org.hl7.fhir.utilities.TextFile;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.utilities.validation.ValidationMessage;
 import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.utils.Params;
 
 import java.awt.*;
 import java.io.File;
@@ -21,7 +22,7 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.UUID;
 
-public class Comparison {
+public class ComparisonService {
 
   public static void doLeftRightComparison(String[] args, String dest, ValidationEngine validator) throws IOException {
     // ok now set up the comparison
@@ -39,9 +40,9 @@ public class Comparison {
 
     if (resLeft != null && resRight != null) {
       if (resLeft instanceof StructureDefinition && resRight instanceof StructureDefinition) {
-        Comparison.compareStructureDefinitions(dest, validator, left, right, (StructureDefinition) resLeft, (StructureDefinition) resRight);
+        ComparisonService.compareStructureDefinitions(dest, validator, left, right, (StructureDefinition) resLeft, (StructureDefinition) resRight);
       } else if (resLeft instanceof CapabilityStatement && resRight instanceof CapabilityStatement) {
-        Comparison.compareCapabilityStatements(args, dest, validator, left, right, (CanonicalResource) resLeft, (CanonicalResource) resRight);
+        ComparisonService.compareCapabilityStatements(args, dest, validator, left, right, (CanonicalResource) resLeft, (CanonicalResource) resRight);
       } else
         System.out.println("Unable to compare left resource " + left + " (" + resLeft.fhirType() + ") with right resource " + right + " (" + resRight.fhirType() + ")");
     }
@@ -71,7 +72,7 @@ public class Comparison {
     new JsonParser().setOutputStyle(IParser.OutputStyle.PRETTY).compose(new FileOutputStream(Utilities.path(dest, "CapabilityStatement-intersection.json")), output.getSubset());
     new JsonParser().setOutputStyle(IParser.OutputStyle.PRETTY).compose(new FileOutputStream(Utilities.path(dest, "OperationOutcome-issues.json")), output.getOutcome());
 
-    String destHtml = Utilities.path(dest, "index.html");
+    String destHtml = Utilities.path(dest, "public/index.html");
     File htmlFile = new File(destHtml);
     Desktop.getDesktop().browse(htmlFile.toURI());
     System.out.println("Done");
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidationUtils.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ValidationService.java
similarity index 88%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidationUtils.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ValidationService.java
index eee487e8c..6aacedbb6 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/ValidationUtils.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ValidationService.java
@@ -1,4 +1,4 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.services;
 
 import org.hl7.fhir.r5.context.TerminologyCache;
 import org.hl7.fhir.r5.elementmodel.Manager;
@@ -10,6 +10,7 @@ import org.hl7.fhir.r5.utils.ToolingExtensions;
 import org.hl7.fhir.utilities.TextFile;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.model.*;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -17,13 +18,37 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-public class ValidationUtils {
+public class ValidationService {
+
+  public static ValidationResponse validateSources(ValidationRequest request, ValidationEngine validator) throws Exception {
+    if (request.getCliContext().getProfiles().size() > 0) {
+      System.out.println("  .. validate " + request.listSourceFiles() + " against " + request.getCliContext().getProfiles().toString());
+    } else {
+      System.out.println("  .. validate " + request.listSourceFiles());
+    }
+    validator.prepare(); // generate any missing snapshots
+
+    ValidationResponse response = new ValidationResponse();
+    for (FileInfo fp : request.getFilesToValidate()) {
+      OperationOutcome operationOutcome = validator.validate(fp.getFileContent().getBytes(), fp.getFileType(),
+        request.getCliContext().getProfiles());
+      ValidationOutcome outcome = new ValidationOutcome();
+
+      // Need to set file content to null as server can't handle json in json
+      fp.setFileContent(null);
+      outcome.setFileInfo(fp);
+      operationOutcome.getIssue().forEach(outcome::addIssue);
+      response.addOutcome(outcome);
+    }
+    return response;
+  }
 
   public static void validateSources(CliContext cliContext, ValidationEngine validator) throws Exception {
-    if (cliContext.getProfiles().size() > 0)
+    if (cliContext.getProfiles().size() > 0) {
       System.out.println("  .. validate " + cliContext.getSources() + " against " + cliContext.getProfiles().toString());
-    else
+    } else {
       System.out.println("  .. validate " + cliContext.getSources());
+    }
     validator.prepare(); // generate any missing snapshots
     Resource r = validator.validate(cliContext.getSources(), cliContext.getProfiles());
     int ec = 0;
@@ -154,7 +179,7 @@ public class ValidationUtils {
     validator.setAnyExtensionsAllowed(cliContext.isAnyExtensionsAllowed());
     validator.setLanguage(cliContext.getLang());
     validator.setLocale(cliContext.getLocale());
-    validator.setSnomedExtension(cliContext.getSnomedCT());
+    validator.setSnomedExtension(cliContext.getSnomedCTCode());
     validator.setAssumeValidRestReferences(cliContext.isAssumeValidRestReferences());
     validator.setNoExtensibleBindingMessages(cliContext.isNoExtensibleBindingMessages());
     TerminologyCache.setNoCaching(cliContext.isNoInternalCaching());
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Common.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Common.java
similarity index 88%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Common.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Common.java
index 66e617399..f13de0b4e 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Common.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Common.java
@@ -1,4 +1,4 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.utils;
 
 import org.hl7.fhir.r5.model.Constants;
 import org.hl7.fhir.r5.model.FhirPublication;
@@ -75,11 +75,9 @@ public class Common {
     }
   }
 
-  public static ValidationEngine getValidationEngine(String[] args, String txLog) throws Exception {
-    String v = Common.getVersion(args);
-    String definitions = VersionUtilities.packageForVersion(v) + "#" + v;
-    System.out.println("Loading (v = " + v + ", tx server http://tx.fhir.org)");
-    return new ValidationEngine(definitions, "http://tx.fhir.org", txLog, FhirPublication.fromCode(v), v);
+  public static ValidationEngine getValidationEngine(String version, String definitions, String txLog) throws Exception {
+    System.out.println("Loading (v = " + version + ", tx server http://tx.fhir.org)");
+    return new ValidationEngine(definitions, "http://tx.fhir.org", txLog, FhirPublication.fromCode(version), version);
   }
 
 }
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Display.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Display.java
similarity index 99%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Display.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Display.java
index 4bfda8ecc..f06fe27cf 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Display.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Display.java
@@ -1,4 +1,4 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.utils;
 
 import org.hl7.fhir.r5.model.Constants;
 import org.hl7.fhir.utilities.VersionUtilities;
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Params.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Params.java
similarity index 98%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Params.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Params.java
index 115b51397..ee465e372 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/Params.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Params.java
@@ -1,7 +1,8 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.utils;
 
 import org.hl7.fhir.utilities.VersionUtilities;
 import org.hl7.fhir.validation.Validator;
+import org.hl7.fhir.validation.cli.model.CliContext;
 
 import java.io.File;
 import java.util.Arrays;
@@ -9,6 +10,7 @@ import java.util.Locale;
 
 public class Params {
 
+  public static final String GUI = "-gui";
   public static final String VERSION = "-version";
   public static final String OUTPUT = "-output";
   public static final String PROXY = "-proxy";
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/SnomedVersion.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/SnomedVersion.java
similarity index 65%
rename from org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/SnomedVersion.java
rename to org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/SnomedVersion.java
index 84a33a65e..3be055e5f 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/SnomedVersion.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/SnomedVersion.java
@@ -1,6 +1,8 @@
-package org.hl7.fhir.validation.cli;
+package org.hl7.fhir.validation.cli.utils;
 
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Optional;
 
 public enum SnomedVersion {
@@ -32,15 +34,15 @@ public enum SnomedVersion {
     return code;
   }
 
-  public static String resolveSnomedCTCode(String s) {
-    String foundCode;
-    Optional<SnomedVersion> opt = Arrays.stream(values())
-      .filter(v -> v.lang.equals(s))
-      .findFirst();
-    if (opt.isPresent()) {
-      return opt.get().code;
-    } else {
-      throw new Error("Snomed edition '" + s + "' not known");
+  public static SnomedVersion getFromCode(String code) {
+    return lookup.get(code);
+  }
+
+  private static final Map<String, SnomedVersion> lookup = new HashMap<>();
+
+  static {
+    for (SnomedVersion s : SnomedVersion.values()) {
+      lookup.put(s.getCode(), s);
     }
   }
 }
diff --git a/org.hl7.fhir.validation/src/main/resources/public/assets/fhir-logo-www.png b/org.hl7.fhir.validation/src/main/resources/public/assets/fhir-logo-www.png
new file mode 100644
index 000000000..90cb7dc81
Binary files /dev/null and b/org.hl7.fhir.validation/src/main/resources/public/assets/fhir-logo-www.png differ
diff --git a/org.hl7.fhir.validation/src/main/resources/public/assets/json-svgrepo-com.svg b/org.hl7.fhir.validation/src/main/resources/public/assets/json-svgrepo-com.svg
new file mode 100644
index 000000000..5643327d1
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/assets/json-svgrepo-com.svg
@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!-- Generator: Adobe Illustrator 18.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 58 58" style="enable-background:new 0 0 58 58;" xml:space="preserve">
+<g>
+	<path d="M33.655,45.988c-0.232-0.31-0.497-0.533-0.793-0.67s-0.608-0.205-0.937-0.205c-0.337,0-0.658,0.063-0.964,0.191
+		s-0.579,0.344-0.82,0.649s-0.431,0.699-0.567,1.183c-0.137,0.483-0.21,1.075-0.219,1.777c0.009,0.684,0.08,1.267,0.212,1.75
+		s0.314,0.877,0.547,1.183s0.497,0.528,0.793,0.67s0.608,0.212,0.937,0.212c0.337,0,0.658-0.066,0.964-0.198s0.579-0.349,0.82-0.649
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+	<path d="M51.5,39V13.978c0-0.766-0.092-1.333-0.55-1.792L39.313,0.55C38.964,0.201,38.48,0,37.985,0H8.963
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+		c-0.183,0.019-0.355,0.07-0.52,0.157s-0.31,0.193-0.438,0.321s-0.228,0.271-0.301,0.431s-0.109,0.313-0.109,0.458
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+		c-0.214,0.647-0.511,1.185-0.889,1.613s-0.82,0.752-1.326,0.971s-1.06,0.328-1.661,0.328s-1.155-0.109-1.661-0.328
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+		s0.82-0.754,1.326-0.978s1.06-0.335,1.661-0.335s1.155,0.111,1.661,0.335s0.948,0.549,1.326,0.978s0.675,0.964,0.889,1.606
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+		h1.668V54z"/>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+</svg>
diff --git a/org.hl7.fhir.validation/src/main/resources/public/assets/xml-svgrepo-com.svg b/org.hl7.fhir.validation/src/main/resources/public/assets/xml-svgrepo-com.svg
new file mode 100644
index 000000000..d0b7a4375
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/assets/xml-svgrepo-com.svg
@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!-- Generator: Adobe Illustrator 18.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 58 58" style="enable-background:new 0 0 58 58;" xml:space="preserve">
+<g>
+	<path d="M51.5,39V13.978c0-0.766-0.092-1.333-0.55-1.792L39.313,0.55C38.964,0.201,38.48,0,37.985,0H8.963
+		C7.777,0,6.5,0.916,6.5,2.926V39H51.5z M37.5,3.391c0-0.458,0.553-0.687,0.877-0.363l10.095,10.095
+		C48.796,13.447,48.567,14,48.109,14H37.5V3.391z M33.793,18.707c-0.391-0.391-0.391-1.023,0-1.414s1.023-0.391,1.414,0l6,6
+		c0.391,0.391,0.391,1.023,0,1.414l-6,6C35.012,30.902,34.756,31,34.5,31s-0.512-0.098-0.707-0.293
+		c-0.391-0.391-0.391-1.023,0-1.414L39.086,24L33.793,18.707z M24.557,31.667l6-17c0.185-0.521,0.753-0.795,1.276-0.61
+		c0.521,0.184,0.794,0.755,0.61,1.276l-6,17C26.298,32.744,25.912,33,25.5,33c-0.11,0-0.223-0.019-0.333-0.058
+		C24.646,32.759,24.373,32.188,24.557,31.667z M15.793,23.293l6-6c0.391-0.391,1.023-0.391,1.414,0s0.391,1.023,0,1.414L17.914,24
+		l5.293,5.293c0.391,0.391,0.391,1.023,0,1.414C23.012,30.902,22.756,31,22.5,31s-0.512-0.098-0.707-0.293l-6-6
+		C15.402,24.316,15.402,23.684,15.793,23.293z"/>
+	<path d="M6.5,41v15c0,1.009,1.22,2,2.463,2h40.074c1.243,0,2.463-0.991,2.463-2V41H6.5z M22.936,54h-1.9l-1.6-3.801h-0.137
+		L17.576,54h-1.9l2.557-4.895l-2.721-5.182h1.873l1.777,4.102h0.137l1.928-4.102H23.1l-2.721,5.182L22.936,54z M34.666,54h-1.668
+		v-6.932l-2.256,5.605h-1.449l-2.27-5.605V54h-1.668V43.924h1.668l2.994,6.891l2.98-6.891h1.668V54z M43.498,54h-6.303V43.924h1.668
+		v8.832h4.635V54z"/>
+</g>
+<g>
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+</g>
+<g>
+</g>
+<g>
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+<g>
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+<g>
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+<g>
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+<g>
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+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+</svg>
diff --git a/org.hl7.fhir.validation/src/main/resources/public/cliwindow.html b/org.hl7.fhir.validation/src/main/resources/public/cliwindow.html
new file mode 100644
index 000000000..607f775e6
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/cliwindow.html
@@ -0,0 +1,56 @@
+    <!--aside id="sidebar">
+      <div class="">
+        <label>Validation Options</label>
+        <ul>
+            <li><input type="checkbox" id="doNative">doNative</li>
+            <li><input type="checkbox" id="anyExtensionAllowed">anyExtensionAllowed</li>
+            <li><input type="checkbox" id="hintAboutNonMustSupport">hintAboutNonMustSupport</li>
+            <li><input type="checkbox" id="recursive">recursive</li>
+            <li><input type="checkbox" id="doDebug">doDebug</li>
+            <li><input type="checkbox" id="assumeValidRestReferences">assumeValidRestReferences</li>
+            <li><input type="checkbox" name="canDoNative" id="canDoNative">canDoNative</li>
+
+            <li>
+              <label>Map</label>
+              <input type="text" name="map" placeholder="enter map">
+            </li>
+            <li>
+              <label>Output</label>
+              <input type="text" name="output" placeholder="enter output">
+            </li>
+            <li>
+              <label>txServer</label>
+              <input type="text" name="txServer" placeholder="enter txServer">
+            </li>
+            <li>
+              <label>sv</label>
+              <input type="text" name="sv" placeholder="enter sv">
+            </li>
+            <li>
+              <label>txLog</label>
+              <input type="text" name="txLog" placeholder="enter txLog">
+            </li>
+            <li>
+              <label>mapLog</label>
+              <input type="text" name="mapLog" placeholder="enter mapLog">
+            </li>
+            <li>
+              <label>lang</label>
+              <input type="text" name="lang" placeholder="enter lang">
+            </li>
+            <li>
+              <label>fhirpath</label>
+              <input type="text" name="fhirpath" placeholder="enter fhirpath">
+            </li>
+            <li>
+              <label>snomedCT</label>
+              <input type="text" name="snomedCT" placeholder="enter snomedCT">
+            </li>
+            <li>
+              <label>targetVer</label>
+              <input type="text" name="targetVer" placeholder="enter targetVer">
+            </li>
+        </ul>
+        <input id='test_button' class="btn" type="submit" value="Submit">
+      </div>
+    </aside-->
diff --git a/org.hl7.fhir.validation/src/main/resources/public/enums/EngineMode.js b/org.hl7.fhir.validation/src/main/resources/public/enums/EngineMode.js
new file mode 100644
index 000000000..63b88cdec
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/enums/EngineMode.js
@@ -0,0 +1,10 @@
+export const EngineMode {
+  VALIDATION,
+  TRANSFORM,
+  NARRATIVE,
+  SNAPSHOT,
+  SCAN,
+  CONVERT, 
+  FHIRPATH,
+  VERSION
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/enums/FhirFormat.js b/org.hl7.fhir.validation/src/main/resources/public/enums/FhirFormat.js
new file mode 100644
index 000000000..c7df35004
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/enums/FhirFormat.js
@@ -0,0 +1,17 @@
+export const FhirFormat = {
+  XML: {
+    extension:'xml'
+  },
+  JSON: {
+    extension:'json'
+  },
+  TURTLE: {
+    extension:'ttl'
+  },
+  TEXT: {
+    extension:'txt'
+  },
+  VBAR: {
+    extension:'hl7'
+  },
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/enums/IssueSeverity.js b/org.hl7.fhir.validation/src/main/resources/public/enums/IssueSeverity.js
new file mode 100644
index 000000000..89665077f
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/enums/IssueSeverity.js
@@ -0,0 +1,14 @@
+export const IssueSeverity = {
+  FATAL: {
+    code: 'Fatal'
+  },
+  ERROR: {
+    code: 'Error'
+  },
+  WARNING: {
+    code: 'Warning'
+  },
+  INFORMATION: {
+    code: 'Information'
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/enums/Locale.js b/org.hl7.fhir.validation/src/main/resources/public/enums/Locale.js
new file mode 100644
index 000000000..e3195a1d8
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/enums/Locale.js
@@ -0,0 +1,30 @@
+export const Locale = {
+  ENGLISH: {
+    code: 'en',
+    value: 'English'
+  },
+  FRENCH: {
+    code: 'fr',
+    value: 'French'
+  },
+  GERMAN: {
+    code: 'de',
+    value: 'German'
+  },
+  ITALIAN: {
+    code: 'it',
+    value: 'Italian'
+  },
+  JAPANESE: {
+    code: 'ja',
+    value: 'Japanese'
+  },
+  KOREAN: {
+    code: 'ko',
+    value: 'Korean'
+  },
+  CHINESE: {
+    code: 'zh',
+    value: 'Chinese'
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/enums/SnomedVersion.js b/org.hl7.fhir.validation/src/main/resources/public/enums/SnomedVersion.js
new file mode 100644
index 000000000..3f82d797f
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/enums/SnomedVersion.js
@@ -0,0 +1,38 @@
+export const SnomedVersion = {
+  INTL: {
+    value: "intl",
+    code: "900000000000207008"
+  },
+  US: {
+    value: "us",
+    code: "731000124108"
+  },
+  UK: {
+    value: "uk",
+    code: "999000041000000102"
+  },
+  AU: {
+    value: "au",
+    code: "32506021000036107"
+  },
+  CA: {
+    value: "ca",
+    code: "20611000087101"
+  },
+  NL: {
+    value: "nl",
+    code: "11000146104"
+  },
+  SE: {
+    value: "se",
+    code: "45991000052106"
+  },
+  ES: {
+    value: "es",
+    code: "449081005"
+  },
+  DK: {
+    value: "dk",
+    code: "554471000005108"
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/index.html b/org.hl7.fhir.validation/src/main/resources/public/index.html
new file mode 100644
index 000000000..e698edd74
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/index.html
@@ -0,0 +1,99 @@
+<html lang="en"><head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
+  <meta name="description" content="">
+  <meta name="author" content="Mark Iantorno">
+  <meta name="generator" content="Jekyll v3.8.6">
+  <title>FHIR HL7 Resrouce Validator GUI</title>
+
+  <!-- Bootstrap core CSS -->
+  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
+
+  <link rel="canonical" href="https://getbootstrap.com/docs/4.4/examples/offcanvas/">
+  <!-- Favicons -->
+  <meta name="theme-color" content="#563d7c">
+
+  <style>
+    .bd-placeholder-img {
+      font-size: 1.125rem;
+      text-anchor: middle;
+      -webkit-user-select: none;
+      -moz-user-select: none;
+      -ms-user-select: none;
+      user-select: none;
+    }
+
+    @media (min-width: 768px) {
+      .bd-placeholder-img-lg {
+        font-size: 3.5rem;
+      }
+    }
+  </style>
+  <!-- Custom styles for this template -->
+  <link href="style.css" rel="stylesheet">
+</head>
+<body class="bg-light">
+  <main role="main" class="container">
+    <div class="d-flex align-items-center p-3 my-3 text-white-50 bg-secondary rounded shadow-sm">
+      <img class="mr-3" src="./assets/fhir-logo-www.png" alt="" height="48">
+      <div class="lh-100">
+        <h6 class="mb-0 text-white lh-100">FHIR Core Validator</h6>
+        <small class="text-white">Experimental</small>
+      </div>
+    </div>
+
+    <div class="my-3 p-3 bg-white rounded shadow-sm">
+      <div class="d-flex border-bottom border-gray justify-content-between align-items-center w-100">
+        <h6 class="pb-2 mb-0">Files to Validate</h6>
+        <button id="validate_button" class="btn btn-secondary mb-1">Validate</button>
+      </div>
+
+      <div class="accordion" id="accordionExample">
+        <ul id="file_entry_file_list" class="list-group border">
+        </ul>
+      </div>
+
+      <div class="bd-callout bd-callout-info">
+        <small class="d-block text-right mt-3">
+          <input type="file" style="display:none;" id="files" name="files[]" multiple="" >
+          <button type="button" class="btn btn-secondary" onclick="document.getElementById('files').click()">Add Files</button>
+        </small>
+      </div>
+
+      <template id="file_entry_template">
+        <li class="list-unstyled">
+          <div class="card">
+            <div class="card-header" id="headingOne">
+              <div class="d-flex">
+                <div class="d-flex align-items-center">
+                  <img id="file_entry_type_icon" class="bd-placeholder-img mr-2 rounded" src="./assets/json-svgrepo-com.svg" width="32" height="32" preserveaspectratio="xMidYMid slice">
+                  <button id="file_entry_name_field" class="btn btn-link" type="button" data-toggle="collapse" data-target="#file_entry_collapse_section" aria-expanded="true" aria-controls="file_entry_collapse_section">
+                    Collapsible Group Item #1
+                  </button>
+                </div>
+                <div class="ml-auto d-flex">
+                  <svg id="file_entry_delete_button" class="delete_button align-self-center" height="24" viewBox="0 0 24 24" width="24">
+                    <path d="M6 19c0 1.1.9 2 2 2h8c1.1 0 2-.9 2-2V7H6v12zm2.46-7.12l1.41-1.41L12 12.59l2.12-2.12 1.41 1.41L13.41 14l2.12 2.12-1.41 1.41L12 15.41l-2.12 2.12-1.41-1.41L10.59 14l-2.13-2.12zM15.5 4l-1-1h-5l-1 1H5v2h14V4z"></path>
+                  </svg>
+                </div>
+              </div>
+            </div>
+
+            <div id="file_entry_collapse_section" class="collapse" aria-labelledby="headingOne" data-parent="#accordionExample">
+              <div class="card-body">
+                <ul id="file_entry_outcome_list" class="list-group">
+                </ul>
+              </div>
+            </div>
+          </div>
+        </li>
+      </template>
+    </div>
+  </main>
+  <script type="module" src="./main.js"></script>
+
+  <!-- jQuery first, then Popper.js, then Bootstrap JS -->
+  <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
+  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
+  <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
+</body></html>
diff --git a/org.hl7.fhir.validation/src/main/resources/public/main.js b/org.hl7.fhir.validation/src/main/resources/public/main.js
new file mode 100644
index 000000000..76ddbc1d1
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/main.js
@@ -0,0 +1,206 @@
+import {CliContext} from './model/CliContext.js';
+import {ValidationRequest} from './model/ValidationRequest.js';
+import {FileInfo} from './model/FileInfo.js';
+import {FhirFormat} from './enums/FhirFormat.js';
+import {IssueSeverity} from './enums/IssueSeverity.js';
+
+/*
+  <Constants>
+*/
+
+// Icon Constants
+const jsonIcon = './assets/json-svgrepo-com.svg';
+const xmlIcon = './assets/xml-svgrepo-com.svg';
+
+// HTML classes
+const CLASS_LIST_ITEM_PLAIN = "list-group-item";
+const CLASS_LIST_ITEM_FATAL = "list-group-item list-group-item-dark";
+const CLASS_LIST_ITEM_ERROR = "list-group-item list-group-item-danger";
+const CLASS_LIST_ITEM_WARNING = "list-group-item list-group-item-warning";
+const CLASS_LIST_ITEM_INFORMATION = "list-group-item list-group-item-info";
+
+// HTML IDs
+const ID_FILE_ENTRY_TEMPLATE = '#file_entry_template';
+const ID_FILE_ENTRY_NAME = 'file_entry_name_field';
+const ID_FILE_ENTRY_ICON = 'file_entry_type_icon';
+const ID_FILE_ENTRY_DELETE_BUTTON = 'file_entry_delete_button';
+const ID_FILE_ENTRY_FILE_LIST = 'file_entry_file_list';
+const ID_FILE_ENTRY_OUTCOME_LIST = 'file_entry_outcome_list';
+const ID_FILE_ENTRY_COLLAPSE_SECTION = 'file_entry_collapse_section';
+
+/*
+  </Constants>
+*/
+
+// Data Fields
+const cli = new CliContext();
+const filesToValidate = [];
+
+document.getElementById('validate_button').addEventListener("click", validateCurrentFiles);
+document.getElementById('files').addEventListener('change', handleFileSelect, false);
+
+// File reading
+function handleFileSelect(evt) {
+  var files = evt.target.files;
+  var output = [];
+  for (var i = 0, f; f = files[i]; i++) {
+    generateFileEntry(f);
+    // Check for proper file type here
+    console.log(f.type);
+  }
+}
+
+function generateFileEntry(file) {
+  var fr = new FileReader();
+  fr.onload = function(e) {
+    // TODO there may be timing issues here
+    filesToValidate.push(new FileInfo(file.name, e.target.result, file.type));
+    document.getElementById(ID_FILE_ENTRY_FILE_LIST).appendChild(generateNewFileListItemFromTemplate(file, filesToValidate.length - 1));
+  };
+  fr.readAsText(file);
+}
+
+// File List Template Generation
+
+function generateNewFileListItemFromTemplate(file, index) {
+  var template = document.querySelector(ID_FILE_ENTRY_TEMPLATE);
+  var clone = template.content.cloneNode(true);
+
+  // Add file name
+  clone.getElementById(ID_FILE_ENTRY_NAME).textContent = file.name;
+
+  // Add appropriate icon for filetype
+  if (file.type.includes(FhirFormat.JSON.extension)) {
+    clone.getElementById(ID_FILE_ENTRY_ICON).src = jsonIcon;
+  } else if (file.type.includes(FhirFormat.XML.extension)) {
+    clone.getElementById(ID_FILE_ENTRY_ICON).src = xmlIcon;
+  }
+
+  clone.getElementById(ID_FILE_ENTRY_COLLAPSE_SECTION).setAttribute("id", (ID_FILE_ENTRY_COLLAPSE_SECTION + index));
+  clone.getElementById(ID_FILE_ENTRY_NAME).setAttribute("aria-controls", (ID_FILE_ENTRY_COLLAPSE_SECTION + index));
+  clone.getElementById(ID_FILE_ENTRY_NAME).setAttribute("data-target", ('#' + ID_FILE_ENTRY_COLLAPSE_SECTION + index));
+
+  // Add delete listener
+  clone.getElementById(ID_FILE_ENTRY_DELETE_BUTTON).addEventListener("click", handleDeleteOnFileList);
+
+  return clone;
+}
+
+function addIssueToFileEntryList(index, severity, details) {
+  var ul = document.getElementById(ID_FILE_ENTRY_FILE_LIST);
+  var listItems = ul.children;
+  var fileEntry = listItems[index];
+  console.log(fileEntry);
+  var listOfIssues = fileEntry.querySelector('#' + ID_FILE_ENTRY_OUTCOME_LIST);
+  var issueItem = createIssueListItem(severity, details);
+  listOfIssues.appendChild(issueItem);
+}
+
+function createIssueListItem(severity, details) {
+  var newIssue = document.createElement('li');
+  switch(severity) {
+    case IssueSeverity.FATAL.code:
+      newIssue.setAttribute("class", CLASS_LIST_ITEM_FATAL);
+      break;
+    case IssueSeverity.ERROR.code:
+      newIssue.setAttribute("class", CLASS_LIST_ITEM_ERROR);
+      break;
+    case IssueSeverity.WARNING.code:
+      newIssue.setAttribute("class", CLASS_LIST_ITEM_WARNING);
+      break;
+    case IssueSeverity.INFORMATION.code:
+      newIssue.setAttribute("class", CLASS_LIST_ITEM_INFORMATION);
+      break;
+    default:
+      console.error('Passed in bad severity: ' + severity);
+  }
+  newIssue.innerHTML = details;
+  return newIssue;
+}
+
+function handleDeleteOnFileList(e) {
+  var li = e.target.closest('li');
+  var nodes = Array.from( li.closest('ul').children );
+  var index = nodes.indexOf( li );
+  nodes[index].remove();
+  filesToValidate.splice((index - 1), 1);
+  console.log('Index -> ' + index);
+  console.log(filesToValidate);
+}
+
+// Validation
+function validateCurrentFiles() {
+    sendFilesToValidate(filesToValidate);
+}
+
+function sendFilesToValidate(arrayOfFileInfo) {
+  var req = new ValidationRequest();
+  req.filesToValidate = arrayOfFileInfo;
+
+  var xhr = new XMLHttpRequest();
+  xhr.open("POST", 'http://localhost:8080/' + 'validate', true);
+  xhr.setRequestHeader('Content-Type', 'application/json');
+  xhr.send(JSON.stringify(req));
+
+  xhr.onload = function () {
+      const response = '{"outcomes": [{"fileInfo": {"fileName": "account-example.canonical.json", "fileType": "JSON"}, "issues": [{"severity": "Error", "details": "\"null\""}, {"severity": "Error", "details": "Profile http://hl7.org/fhir/StructureDefinition/Account, Element: minimum required = 1, but only found 0"}]}, {"fileInfo": {"fileName": "account-example(example).xml", "fileType": "XML"}, "issues": []}]}';
+      var test = xhr.responseText;
+      processValidationResponse(JSON.parse(JSON.parse(xhr.responseText)));
+  };
+}
+
+function processValidationResponse(validationResponse) {
+  console.log(validationResponse);
+  console.log(validationResponse.length);
+  console.log(validationResponse.outcomes);
+  console.log(validationResponse.outcomes.length);
+
+  for (var i = 0; i < validationResponse.outcomes.length; i++) {
+    console.log(validationResponse.outcomes[i]);
+    var fileInfo = validationResponse.outcomes[i].fileInfo;
+    var issues = validationResponse.outcomes[i].issues;
+    issues.forEach(issue => {
+      console.log(issue);
+      addIssueToFileEntryList(i, issue.severity, issue.details);
+    });
+  }
+
+}
+
+
+
+
+// window.onload = function loadCliContext() {
+//   var xhr = new XMLHttpRequest();
+//   xhr.open("GET", 'http://localhost:8080/currentContext');
+//   xhr.send();
+//   xhr.onreadystatechange = function() {
+//     if (this.readyState == 4 && this.status == 200) {
+//       console.log(xhr.responseText);
+//     }
+//   }
+// }
+
+// /*
+//   Escape JSON
+// */
+// var escapeJSON = exports.escapeJSON = function(json) {
+//   var escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
+//   var meta = {    // table of character substitutions
+//               '\b': '\\b',
+//               '\t': '\\t',
+//               '\n': '\\n',
+//               '\f': '\\f',
+//               '\r': '\\r',
+//               '"' : '\\"',
+//               '\\': '\\\\'
+//             };
+//
+//   escapable.lastIndex = 0;
+//   return escapable.test(json) ? '"' + json.replace(escapable, function (a) {
+//       var c = meta[a];
+//       return (typeof c === 'string') ? c
+//         : '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
+//   }) + '"' : '"' + json + '"';
+//
+// };
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/CliContext.js b/org.hl7.fhir.validation/src/main/resources/public/model/CliContext.js
new file mode 100644
index 000000000..673637cd9
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/CliContext.js
@@ -0,0 +1,34 @@
+import {SnomedVersion} from '../enums/SnomedVersion.js';
+import {Locale} from '../enums/Locale.js';
+
+export class CliContext {
+    constructor(){
+        this.doNative = false;
+        this.anyExtensionsAllowed = true;
+        this.hintAboutNonMustSupport = false;
+        this.recursive = false;
+        this.doDebug = false;
+        this.assumeValidRestReferences = false;
+        this.canDoNative = false;
+
+        this.map = null;
+        this.output = null;
+        this.txServer = "http://tx.fhir.org";
+        this.sv = "current";
+        this.txLog = null;
+        this.mapLog = null;
+        this.lang = null;
+        this.fhirpath = null;
+        this.snomedCT = SnomedVersion.ES.value;
+        this.targetVer = null;
+
+        this.igs = [];
+        this.questionnaires = [];
+        this.profiles = [];
+        this.sources = [];
+
+        this.locale = Locale.ENGLISH.value;
+
+        this.locations = new Map();
+    }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/FileInfo.js b/org.hl7.fhir.validation/src/main/resources/public/model/FileInfo.js
new file mode 100644
index 000000000..d853c1e44
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/FileInfo.js
@@ -0,0 +1,13 @@
+import {FhirFormat} from '../enums/FhirFormat.js';
+
+export class FileInfo {
+    constructor(fileName, fileContent, type){
+        this.fileName = fileName;
+        this.fileContent = fileContent;
+        if (type.includes('json')) {
+          this.fileType = FhirFormat.JSON.extension;
+        } else if (type.includes('xml')) {
+          this.fileType = FhirFormat.XML.extension;
+        }
+    }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/ValidationIssue.js b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationIssue.js
new file mode 100644
index 000000000..0ce182359
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationIssue.js
@@ -0,0 +1,6 @@
+export class ValidationIssue {
+    constructor(){
+        this.severity = "";
+        this.details = "";
+    }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/ValidationOutcome.js b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationOutcome.js
new file mode 100644
index 000000000..77f5e41d0
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationOutcome.js
@@ -0,0 +1,8 @@
+import {FileInfo} from './FileInfo.js';
+
+export class ValidationOutcome {
+    constructor(){
+        this.fileInfo = null;
+        this.issues = [];
+    }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/ValidationRequest.js b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationRequest.js
new file mode 100644
index 000000000..85b7559bb
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationRequest.js
@@ -0,0 +1,8 @@
+import {CliContext} from './CliContext.js';
+
+export class ValidationRequest {
+    constructor(){
+        this.cliContext = new CliContext();
+        this.filesToValidate = [];
+    }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/model/ValidationResponse.js b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationResponse.js
new file mode 100644
index 000000000..d128d3e30
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/model/ValidationResponse.js
@@ -0,0 +1,7 @@
+import {ValidationOutcome} from './ValidationOutcome.js';
+
+export class ValidationResponse {
+  constructor() {
+      this.outcomes = [];
+  }
+}
diff --git a/org.hl7.fhir.validation/src/main/resources/public/style.css b/org.hl7.fhir.validation/src/main/resources/public/style.css
new file mode 100644
index 000000000..1cba70413
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/resources/public/style.css
@@ -0,0 +1,94 @@
+/* */
+.container{
+  width:80%;
+  margin:auto;
+  overflow: hidden;
+}
+
+#main{
+  float: left;
+  width: 70%;
+}
+
+#sidebar{
+  float: right;
+  width: 30%;
+}
+
+
+html,
+body {
+  overflow-x: hidden; /* Prevent scroll on narrow devices */
+}
+
+body {
+  padding-top: 56px;
+}
+
+@media (max-width: 991.98px) {
+  .offcanvas-collapse {
+    position: fixed;
+    top: 56px; /* Height of navbar */
+    bottom: 0;
+    left: 100%;
+    width: 100%;
+    padding-right: 1rem;
+    padding-left: 1rem;
+    overflow-y: auto;
+    visibility: hidden;
+    background-color: #343a40;
+    transition: visibility .3s ease-in-out, -webkit-transform .3s ease-in-out;
+    transition: transform .3s ease-in-out, visibility .3s ease-in-out;
+    transition: transform .3s ease-in-out, visibility .3s ease-in-out, -webkit-transform .3s ease-in-out;
+  }
+  .offcanvas-collapse.open {
+    visibility: visible;
+    -webkit-transform: translateX(-100%);
+    transform: translateX(-100%);
+  }
+}
+
+.nav-scroller {
+  position: relative;
+  z-index: 2;
+  height: 2.75rem;
+  overflow-y: hidden;
+}
+
+.nav-scroller .nav {
+  display: -ms-flexbox;
+  display: flex;
+  -ms-flex-wrap: nowrap;
+  flex-wrap: nowrap;
+  padding-bottom: 1rem;
+  margin-top: -1px;
+  overflow-x: auto;
+  color: rgba(255, 255, 255, .75);
+  text-align: center;
+  white-space: nowrap;
+  -webkit-overflow-scrolling: touch;
+}
+
+.nav-underline .nav-link {
+  padding-top: .75rem;
+  padding-bottom: .75rem;
+  font-size: .875rem;
+  color: #6c757d;
+}
+
+.nav-underline .nav-link:hover {
+  color: #007bff;
+}
+
+.nav-underline .active {
+  font-weight: 500;
+  color: #343a40;
+}
+
+.text-white-50 { color: rgba(255, 255, 255, .5); }
+
+.bg-purple { background-color: #6f42c1; }
+
+.lh-100 { line-height: 1; }
+.lh-125 { line-height: 1.25; }
+.lh-150 { line-height: 1.5; }
diff --git a/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/BaseRestTest.java b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/BaseRestTest.java
new file mode 100644
index 000000000..cd3a88874
--- /dev/null
+++ b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/BaseRestTest.java
@@ -0,0 +1,36 @@
+package org.hl7.fhir.validation.cli;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.http.HttpResponse;
+import org.apache.http.util.EntityUtils;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+
+import java.io.IOException;
+
+public abstract class BaseRestTest {
+
+  protected final String JSON_MIME_TYPE = "application/json";
+
+  @BeforeAll
+  public static void startServer() {
+    ValidatorGui.start(new CliContext(), null, false);
+  }
+
+  @AfterAll
+  public static void stopServer() {
+    ValidatorGui.stop();
+  }
+
+  public static <T> T retrieveResourceFromResponse(HttpResponse response, Class<T> clazz)
+    throws IOException {
+
+    String jsonFromResponse = EntityUtils.toString(response.getEntity());
+    ObjectMapper mapper = new ObjectMapper()
+      .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+    return mapper.readValue(jsonFromResponse, clazz);
+  }
+
+}
diff --git a/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/ValidatorGuiTest.java b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/ValidatorGuiTest.java
new file mode 100644
index 000000000..b8e88e779
--- /dev/null
+++ b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/ValidatorGuiTest.java
@@ -0,0 +1,33 @@
+package org.hl7.fhir.validation.cli;
+
+import io.github.bonigarcia.wdm.WebDriverManager;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.openqa.selenium.WebDriver;
+import org.openqa.selenium.chrome.ChromeDriver;
+import org.openqa.selenium.chrome.ChromeOptions;
+
+import java.io.IOException;
+
+class ValidatorGuiTest {
+
+  private final String HTML_TITLE_TAG = "<title>FHIR HL7 Resrouce Validator GUI</title>";
+
+  @Test
+  @DisplayName("Page boots correctly, and displays index.html")
+  public void UI_contains_correct_heading() throws IOException {
+    ValidatorGui.start(new CliContext(), null, false);
+    WebDriverManager.chromedriver().setup();
+    ChromeOptions options = new ChromeOptions();
+    options.addArguments("--headless");
+    options.addArguments("--disable-gpu");
+    WebDriver driver = new ChromeDriver(options);
+    driver.get("http://localhost:8080/home");
+
+    Assertions.assertTrue(driver.getPageSource().contains(HTML_TITLE_TAG));
+    driver.quit();
+    ValidatorGui.stop();
+  }
+}
\ No newline at end of file
diff --git a/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpGetContextTest.java b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpGetContextTest.java
new file mode 100644
index 000000000..ac10cd47a
--- /dev/null
+++ b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpGetContextTest.java
@@ -0,0 +1,47 @@
+package org.hl7.fhir.validation.cli.controller;
+
+import org.apache.http.HttpResponse;
+import org.apache.http.HttpStatus;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.methods.HttpUriRequest;
+import org.apache.http.entity.ContentType;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.hl7.fhir.validation.cli.BaseRestTest;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+class HttpGetContextTest extends BaseRestTest {
+
+  private final String GET_CONTEXT_URL = "http://localhost:8080/context";
+
+  @Test
+  @DisplayName("Testing status code on get context endpoint.")
+  public void testStatus() throws IOException {
+    HttpUriRequest request = new HttpGet(GET_CONTEXT_URL);
+    HttpResponse httpResponse = HttpClientBuilder.create().build().execute(request);
+    Assertions.assertEquals(httpResponse.getStatusLine().getStatusCode(), HttpStatus.SC_OK);
+  }
+
+  @Test
+  @DisplayName("Testing media type on get context endpoint.")
+  public void testMediaType() throws IOException {
+    HttpUriRequest request = new HttpGet(GET_CONTEXT_URL);
+    HttpResponse httpResponse = HttpClientBuilder.create().build().execute(request);
+    String mimeType = ContentType.getOrDefault(httpResponse.getEntity()).getMimeType();
+    Assertions.assertEquals(JSON_MIME_TYPE, mimeType );
+  }
+
+  @Test
+  @DisplayName("Testing status code on get context endpoint.")
+  public void testJSONPayload() throws IOException {
+    HttpUriRequest request = new HttpGet(GET_CONTEXT_URL);
+    HttpResponse httpResponse = HttpClientBuilder.create().build().execute(request);
+    CliContext resource = retrieveResourceFromResponse(httpResponse, CliContext.class);
+    Assertions.assertEquals(new CliContext(), resource);
+  }
+
+}
\ No newline at end of file
diff --git a/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpPutContextTest.java b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpPutContextTest.java
new file mode 100644
index 000000000..5c967191e
--- /dev/null
+++ b/org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/controller/HttpPutContextTest.java
@@ -0,0 +1,24 @@
+package org.hl7.fhir.validation.cli.controller;
+
+import io.javalin.http.Context;
+
+import org.junit.jupiter.api.Test;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+class HttpPutContextTest {
+
+  public CliContextController myCliContextController;
+
+  public HttpPutContextTest() {
+    this.myCliContextController = new CliContextController(null);
+  }
+
+  @Test
+  void handleSetCurrentCliContext() {
+    Context context = mock(Context.class);
+    this.myCliContextController.handleSetCurrentCliContext(context);
+    verify(context).status(200);
+  }
+}
\ No newline at end of file
diff --git a/org.hl7.fhir.validation/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker b/org.hl7.fhir.validation/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
new file mode 100644
index 000000000..ca6ee9cea
--- /dev/null
+++ b/org.hl7.fhir.validation/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
@@ -0,0 +1 @@
+mock-maker-inline
\ No newline at end of file