diff --git a/Gemfile b/Gemfile
index 6a621c456d4..ffa12dfe510 100644
--- a/Gemfile
+++ b/Gemfile
@@ -203,6 +203,8 @@ gem "sassc-rails"
 gem 'rotp'
 gem 'rqrcode'
 
+gem 'rubyzip', require: false
+
 gem 'sshkey', require: false
 
 gem 'rchardet', require: false
diff --git a/Gemfile.lock b/Gemfile.lock
index 898e8b7658d..194ec34d1e7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -351,6 +351,7 @@ GEM
       guess_html_encoding (>= 0.0.4)
       nokogiri (>= 1.6.0)
     ruby_dep (1.5.0)
+    rubyzip (1.2.3)
     safe_yaml (1.0.5)
     sanitize (5.0.0)
       crass (~> 1.0.2)
@@ -516,6 +517,7 @@ DEPENDENCIES
   rubocop
   ruby-prof
   ruby-readability
+  rubyzip
   sanitize
   sassc
   sassc-rails
diff --git a/app/assets/javascripts/admin/templates/modal/admin-install-theme.hbs b/app/assets/javascripts/admin/templates/modal/admin-install-theme.hbs
index 153dbc9e8f1..a41bfa93a94 100644
--- a/app/assets/javascripts/admin/templates/modal/admin-install-theme.hbs
+++ b/app/assets/javascripts/admin/templates/modal/admin-install-theme.hbs
@@ -44,7 +44,7 @@
 
     {{#if local}}
       <div class="inputs">
-        <input onchange={{action "uploadLocaleFile"}} type="file" id="file-input" accept='.dcstyle.json,application/json,.tar.gz,application/x-gzip'><br>
+        <input onchange={{action "uploadLocaleFile"}} type="file" id="file-input" accept='.dcstyle.json,application/json,.tar.gz,application/x-gzip,.zip,application/zip'><br>
         <span class="description">{{i18n 'admin.customize.theme.import_file_tip'}}</span>
       </div>
     {{/if}}
diff --git a/app/controllers/admin/themes_controller.rb b/app/controllers/admin/themes_controller.rb
index 5389269af87..4def5bd2149 100644
--- a/app/controllers/admin/themes_controller.rb
+++ b/app/controllers/admin/themes_controller.rb
@@ -88,7 +88,7 @@ class Admin::ThemesController < Admin::AdminController
       rescue RemoteTheme::ImportError => e
         render_json_error e.message
       end
-    elsif params[:bundle] || (params[:theme] && ["application/x-gzip", "application/gzip"].include?(params[:theme].content_type))
+    elsif params[:bundle] || (params[:theme] && ["application/x-gzip", "application/gzip", "application/zip"].include?(params[:theme].content_type))
       # params[:bundle] used by theme CLI. params[:theme] used by admin UI
       bundle = params[:bundle] || params[:theme]
       theme_id = params[:theme_id]
@@ -252,6 +252,7 @@ class Admin::ThemesController < Admin::AdminController
 
     exporter = ThemeStore::TgzExporter.new(@theme)
     file_path = exporter.package_filename
+
     headers['Content-Length'] = File.size(file_path).to_s
     send_data File.read(file_path),
       filename: File.basename(file_path),
diff --git a/app/jobs/regular/export_csv_file.rb b/app/jobs/regular/export_csv_file.rb
index e1b57398c1a..d8d3a7204ec 100644
--- a/app/jobs/regular/export_csv_file.rb
+++ b/app/jobs/regular/export_csv_file.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'csv'
+require 'zip'
 require_dependency 'system_message'
 require_dependency 'upload_creator'
 
@@ -53,18 +54,19 @@ module Jobs
       # ensure directory exists
       FileUtils.mkdir_p(UserExport.base_directory) unless Dir.exists?(UserExport.base_directory)
 
-      # write to CSV file
-      CSV.open(absolute_path, "w") do |csv|
+      # Generate a compressed CSV file
+      csv_to_export = CSV.generate do |csv|
         csv << get_header if @entity != "report"
         public_send(export_method).each { |d| csv << d }
       end
 
-      # compress CSV file
-      system('gzip', '-5', absolute_path)
+      compressed_file_path = "#{absolute_path}.zip"
+      Zip::File.open(compressed_file_path, Zip::File::CREATE) do |zipfile|
+        zipfile.get_output_stream(file_name) { |f| f.puts csv_to_export }
+      end
 
       # create upload
       upload = nil
-      compressed_file_path = "#{absolute_path}.gz"
 
       if File.exist?(compressed_file_path)
         File.open(compressed_file_path) do |file|
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index 4e01d15691b..47f8dacca23 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -3517,7 +3517,7 @@ en:
           delete_upload_confirm: "Delete this upload? (Theme CSS may stop working!)"
           import_web_tip: "Repository containing theme"
           import_web_advanced: "Advanced..."
-          import_file_tip: ".tar.gz or .dcstyle.json file containing theme"
+          import_file_tip: ".tar.gz, .zip, or .dcstyle.json file containing theme"
           is_private: "Theme is in a private git repository"
           remote_branch: "Branch name (optional)"
           public_key: "Grant the following public key access to the repo:"
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 0a7a0af6098..6fa93ed7b29 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -2671,7 +2671,7 @@ en:
 
         The above download link will be valid for 48 hours.
 
-        The data is compressed as a gzip archive. If the archive does not extract itself when you open it, use the tools recommended here: https://www.gzip.org/#faq4
+        The data is compressed as a zip archive. If the archive does not extract itself when you open it, use the tool recommended here: https://www.7-zip.org/
 
     csv_export_failed:
       title: "CSV Export Failed"
diff --git a/config/site_settings.yml b/config/site_settings.yml
index ebe51f6082e..3b5736ccd28 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -1057,7 +1057,7 @@ files:
     list_type: compact
   export_authorized_extensions:
     hidden: true
-    default: "gz"
+    default: "zip"
     type: list
     list_type: compact
   responsive_post_image_sizes:
diff --git a/lib/import_export/zip_utils.rb b/lib/import_export/zip_utils.rb
new file mode 100644
index 00000000000..dc06e0efb07
--- /dev/null
+++ b/lib/import_export/zip_utils.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'zip'
+
+class ZipUtils
+  def zip_directory(path, export_name)
+    zip_filename = "#{export_name}.zip"
+    absolute_path = "#{path}/#{export_name}"
+    entries = Dir.entries(absolute_path) - %w[. ..]
+
+    Zip::File.open(zip_filename, Zip::File::CREATE) do |zipfile|
+      write_entries(entries, absolute_path, '', zipfile)
+    end
+
+    "#{absolute_path}.zip"
+  end
+
+  def unzip_directory(path, zip_filename, allow_non_root_folder: false)
+    Zip::File.open(zip_filename) do |zip_file|
+      root = root_folder_present?(zip_file, allow_non_root_folder) ? '' : 'unzipped/'
+      zip_file.each do |entry|
+        entry_path = File.join(path, "#{root}#{entry.name}")
+        FileUtils.mkdir_p(File.dirname(entry_path))
+        entry.extract(entry_path)
+      end
+    end
+  end
+
+  private
+
+  def root_folder_present?(filenames, allow_non_root_folder)
+    filenames.map { |p| p.name.split('/').first }.uniq!.size == 1 || allow_non_root_folder
+  end
+
+  # A helper method to make the recursion work.
+  def write_entries(entries, base_path, path, zipfile)
+    entries.each do |e|
+      zipfile_path = path == '' ? e : File.join(path, e)
+      disk_file_path = File.join(base_path, zipfile_path)
+
+      if File.directory? disk_file_path
+        recursively_deflate_directory(disk_file_path, zipfile, base_path, zipfile_path)
+      else
+        put_into_archive(disk_file_path, zipfile, zipfile_path)
+      end
+    end
+  end
+
+  def recursively_deflate_directory(disk_file_path, zipfile, base_path, zipfile_path)
+    zipfile.mkdir zipfile_path
+    subdir = Dir.entries(disk_file_path) - %w[. ..]
+    write_entries subdir, base_path, zipfile_path, zipfile
+  end
+
+  def put_into_archive(disk_file_path, zipfile, zipfile_path)
+    zipfile.add(zipfile_path, disk_file_path)
+  end
+end
diff --git a/lib/theme_store/tgz_exporter.rb b/lib/theme_store/tgz_exporter.rb
index 824a874ab94..75f5bff8963 100644
--- a/lib/theme_store/tgz_exporter.rb
+++ b/lib/theme_store/tgz_exporter.rb
@@ -56,14 +56,10 @@ class ThemeStore::TgzExporter
   end
 
   private
+
   def export_package
     export_to_folder
-    Dir.chdir(@temp_folder) do
-      tar_filename = "#{@export_name}.tar"
-      Discourse::Utils.execute_command('tar', '--create', '--file', tar_filename, @export_name, failure_message: "Failed to tar theme.")
-      Discourse::Utils.execute_command('gzip', '-5', tar_filename, failure_message: "Failed to gzip archive.")
-      "#{@temp_folder}/#{tar_filename}.gz"
-    end
-  end
 
+    Dir.chdir(@temp_folder) { ZipUtils.new.zip_directory(@temp_folder, @export_name) }
+  end
 end
diff --git a/lib/theme_store/tgz_importer.rb b/lib/theme_store/tgz_importer.rb
index 5dfb0716e68..f0c88a4d1fd 100644
--- a/lib/theme_store/tgz_importer.rb
+++ b/lib/theme_store/tgz_importer.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'import_export/zip_utils'
+
 module ThemeStore; end
 
 class ThemeStore::TgzImporter
@@ -13,8 +15,16 @@ class ThemeStore::TgzImporter
 
   def import!
     FileUtils.mkdir(@temp_folder)
+
     Dir.chdir(@temp_folder) do
-      Discourse::Utils.execute_command("tar", "-xzvf", @filename, "--strip", "1")
+      if @filename.include?('.zip')
+        ZipUtils.new.unzip_directory(@temp_folder, @filename)
+
+        # --strip 1 equivalent
+        FileUtils.mv(Dir.glob("#{@temp_folder}/*/*"), @temp_folder)
+      else
+        Discourse::Utils.execute_command("tar", "-xzvf", @filename, "--strip", "1")
+      end
     end
   rescue RuntimeError
     raise RemoteTheme::ImportError, I18n.t("themes.import_error.unpack_failed")
@@ -44,7 +54,7 @@ class ThemeStore::TgzImporter
 
   def all_files
     Dir.chdir(@temp_folder) do
-      Dir.glob("**/*").reject { |f| File.directory?(f) }
+      Dir.glob("**/**").reject { |f| File.directory?(f) }
     end
   end
 
diff --git a/spec/components/theme_store/tgz_exporter_spec.rb b/spec/components/theme_store/tgz_exporter_spec.rb
index b66bf6e1b08..18266eeb263 100644
--- a/spec/components/theme_store/tgz_exporter_spec.rb
+++ b/spec/components/theme_store/tgz_exporter_spec.rb
@@ -2,6 +2,7 @@
 
 require 'rails_helper'
 require 'theme_store/tgz_exporter'
+require 'import_export/zip_utils'
 
 describe ThemeStore::TgzExporter do
   let!(:theme) do
@@ -55,15 +56,17 @@ describe ThemeStore::TgzExporter do
     filename = exporter.package_filename
     FileUtils.cp(filename, dir)
     exporter.cleanup!
-    "#{dir}/discourse-header-icons.tar.gz"
+    "#{dir}/discourse-header-icons.zip"
   end
 
   it "exports the theme correctly" do
     package
-    Dir.chdir("#{dir}") do
-      `tar -xzf discourse-header-icons.tar.gz`
-    end
-    Dir.chdir("#{dir}/discourse-header-icons") do
+    file = 'discourse-header-icons.zip'
+    dest = 'discourse-header-icons'
+    Dir.chdir(dir) do
+      ZipUtils.new.unzip_directory(dir, file, allow_non_root_folder: true)
+      `rm #{file}`
+
       folders = Dir.glob("**/*").reject { |f| File.file?(f) }
       expect(folders).to contain_exactly("assets", "common", "locales", "mobile")
 
@@ -121,7 +124,7 @@ describe ThemeStore::TgzExporter do
     exporter = ThemeStore::TgzExporter.new(theme)
     filename = exporter.package_filename
     exporter.cleanup!
-    expect(filename).to end_with "/discourse-header-icons.tar.gz"
+    expect(filename).to end_with "/discourse-header-icons.zip"
   end
 
 end
diff --git a/spec/components/theme_store/tgz_importer_spec.rb b/spec/components/theme_store/tgz_importer_spec.rb
index 2986b1d2c9c..0aad92584e8 100644
--- a/spec/components/theme_store/tgz_importer_spec.rb
+++ b/spec/components/theme_store/tgz_importer_spec.rb
@@ -4,26 +4,41 @@
 
 require 'rails_helper'
 require 'theme_store/tgz_importer'
+require 'import_export/zip_utils'
 
 describe ThemeStore::TgzImporter do
   before do
     @temp_folder = "#{Pathname.new(Dir.tmpdir).realpath}/discourse_theme_#{SecureRandom.hex}"
+
+    FileUtils.mkdir(@temp_folder)
+    Dir.chdir(@temp_folder) do
+      FileUtils.mkdir_p('test/a')
+      File.write("test/hello.txt", "hello world")
+      File.write("test/a/inner", "hello world inner")
+    end
   end
 
   after do
     FileUtils.rm_rf @temp_folder
   end
 
-  it "can import a simple theme" do
-
-    FileUtils.mkdir(@temp_folder)
-
+  it "can import a simple zipped theme" do
     Dir.chdir(@temp_folder) do
-      FileUtils.mkdir('test/')
-      File.write("test/hello.txt", "hello world")
-      FileUtils.mkdir('test/a')
-      File.write("test/a/inner", "hello world inner")
+      ZipUtils.new.zip_directory(@temp_folder, 'test')
+      FileUtils.rm_rf('test/')
+    end
 
+    importer = ThemeStore::TgzImporter.new("#{@temp_folder}/test.zip")
+    importer.import!
+
+    expect(importer["hello.txt"]).to eq("hello world")
+    expect(importer["a/inner"]).to eq("hello world inner")
+
+    importer.cleanup!
+  end
+
+  it "can import a simple gzipped theme" do
+    Dir.chdir(@temp_folder) do
       `tar -cvzf test.tar.gz test/* 2> /dev/null`
     end
 
diff --git a/spec/components/validators/upload_validator_spec.rb b/spec/components/validators/upload_validator_spec.rb
index e9a3dfe601a..9348c85e79a 100644
--- a/spec/components/validators/upload_validator_spec.rb
+++ b/spec/components/validators/upload_validator_spec.rb
@@ -22,14 +22,14 @@ describe Validators::UploadValidator do
     it "allows 'gz' as extension when uploading export file" do
       SiteSetting.authorized_extensions = ""
 
-      expect(UploadCreator.new(csv_file, "#{filename}.gz", for_export: true).create_for(user.id)).to be_valid
+      expect(UploadCreator.new(csv_file, "#{filename}.zip", for_export: true).create_for(user.id)).to be_valid
     end
 
     it "allows uses max_export_file_size_kb when uploading export file" do
       SiteSetting.max_attachment_size_kb = "0"
-      SiteSetting.authorized_extensions = "gz"
+      SiteSetting.authorized_extensions = "zip"
 
-      expect(UploadCreator.new(csv_file, "#{filename}.gz", for_export: true).create_for(user.id)).to be_valid
+      expect(UploadCreator.new(csv_file, "#{filename}.zip", for_export: true).create_for(user.id)).to be_valid
     end
 
     describe 'when allow_staff_to_upload_any_file_in_pm is true' do
diff --git a/spec/requests/admin/themes_controller_spec.rb b/spec/requests/admin/themes_controller_spec.rb
index 4f32a63e013..43cc16cd8b8 100644
--- a/spec/requests/admin/themes_controller_spec.rb
+++ b/spec/requests/admin/themes_controller_spec.rb
@@ -51,10 +51,10 @@ describe Admin::ThemesController do
       expect(response.status).to eq(200)
 
       # Save the output in a temp file (automatically cleaned up)
-      file = Tempfile.new('archive.tar.gz')
+      file = Tempfile.new('archive.tar.zip')
       file.write(response.body)
       file.rewind
-      uploaded_file = Rack::Test::UploadedFile.new(file.path, "application/x-gzip")
+      uploaded_file = Rack::Test::UploadedFile.new(file.path, "application/zip")
 
       # Now import it again
       expect do