diff --git a/.gitignore b/.gitignore
index 67dcad40e52..8a1f8652b9a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -54,6 +54,7 @@ bootsnap-compile-cache/
 !/plugins/discourse-details/
 !/plugins/discourse-nginx-performance-report
 !/plugins/discourse-narrative-bot
+!/plugins/discourse-presence
 /plugins/*/auto_generated/
 
 /spec/fixtures/plugins/my_plugin/auto_generated
diff --git a/plugins/discourse-presence/README.md b/plugins/discourse-presence/README.md
new file mode 100644
index 00000000000..4e41c6c62ec
--- /dev/null
+++ b/plugins/discourse-presence/README.md
@@ -0,0 +1,14 @@
+# Discourse Presence plugin
+This plugin shows which users are currently writing a reply at the same time as you.
+
+## Installation
+
+Follow the directions at [Install a Plugin](https://meta.discourse.org/t/install-a-plugin/19157) using https://github.com/discourse/discourse-presence.git as the repository URL.
+
+## Authors
+
+André Pereira, David Taylor
+
+## License
+
+GNU GPL v2
diff --git a/plugins/discourse-presence/assets/javascripts/discourse/components/composer-presence-display.js.es6 b/plugins/discourse-presence/assets/javascripts/discourse/components/composer-presence-display.js.es6
new file mode 100644
index 00000000000..44184dd2c8e
--- /dev/null
+++ b/plugins/discourse-presence/assets/javascripts/discourse/components/composer-presence-display.js.es6
@@ -0,0 +1,21 @@
+import computed from 'ember-addons/ember-computed-decorators';
+
+export default Ember.Component.extend({
+  composer: Ember.inject.controller(),
+
+  @computed('composer.presenceUsers', 'currentUser.id')
+  users(presenceUsers, currentUser_id){
+    return presenceUsers.filter(user => user.id !== currentUser_id);
+  },
+
+  @computed('composer.presenceState.action')
+  isReply(action){
+    return action === 'reply';
+  },
+
+  @computed('users.length')
+  shouldDisplay(length){
+    return length > 0;
+  }
+
+});
\ No newline at end of file
diff --git a/plugins/discourse-presence/assets/javascripts/discourse/initializers/composer-controller-presence.js.es6 b/plugins/discourse-presence/assets/javascripts/discourse/initializers/composer-controller-presence.js.es6
new file mode 100644
index 00000000000..0fcdbbb55bd
--- /dev/null
+++ b/plugins/discourse-presence/assets/javascripts/discourse/initializers/composer-controller-presence.js.es6
@@ -0,0 +1,128 @@
+import { ajax } from 'discourse/lib/ajax';
+import { observes}  from 'ember-addons/ember-computed-decorators';
+import { withPluginApi } from 'discourse/lib/plugin-api';
+import pageVisible from 'discourse/lib/page-visible';
+
+function initialize(api) {
+  api.modifyClass('controller:composer', {
+
+    oldPresenceState: { compose_state: 'closed' },
+    presenceState: { compose_state: 'closed' },
+    keepAliveTimer: null,
+    messageBusChannel: null,
+
+    @observes('model.composeState', 'model.action', 'model.post', 'model.topic')
+    openStatusChanged(){
+      Ember.run.once(this, 'updateStateObject');
+    },
+
+    updateStateObject(){
+      const composeState = this.get('model.composeState');
+
+      const stateObject = {
+        compose_state: composeState ? composeState : 'closed'
+      };
+
+      if(stateObject.compose_state === 'open'){
+        stateObject.action = this.get('model.action');
+
+        // Add some context if we're editing or replying
+        switch(stateObject.action){
+          case 'edit':
+            stateObject.post_id = this.get('model.post.id');
+            break;
+          case 'reply':
+            stateObject.topic_id = this.get('model.topic.id');
+            break;
+          default:
+            break; // createTopic or privateMessage
+        }
+      }
+
+      this.set('oldPresenceState', this.get('presenceState'));
+      this.set('presenceState', stateObject);
+    },
+
+    shouldSharePresence(){
+      const isOpen = this.get('presenceState.compose_state') !== 'open';
+      const isEditing = ['edit','reply'].includes(this.get('presenceState.action'));
+      return isOpen && isEditing;
+    },
+
+    @observes('presenceState')
+    presenceStateChanged(){
+      if(this.get('messageBusChannel')){
+        this.messageBus.unsubscribe(this.get('messageBusChannel'));
+        this.set('messageBusChannel', null);
+      }
+
+      this.set('presenceUsers', []);
+
+      ajax('/presence/publish/', {
+        type: 'POST',
+        data: {
+          response_needed: true,
+          previous: this.get('oldPresenceState'),
+          current: this.get('presenceState')
+        }
+      }).then((data) => {
+        const messageBusChannel = data['messagebus_channel'];
+        if(messageBusChannel){
+          const users = data['users'];
+          const messageBusId = data['messagebus_id'];
+          this.set('presenceUsers', users);
+          this.set('messageBusChannel', messageBusChannel);
+          this.messageBus.subscribe(messageBusChannel, message => {
+            this.set('presenceUsers', message['users']);
+          }, messageBusId);
+        }
+      }).catch((error) => {
+        // This isn't a critical failure, so don't disturb the user
+        console.error("Error publishing composer status", error);
+      });
+
+
+      Ember.run.cancel(this.get('keepAliveTimer'));
+      if(this.shouldSharePresence()){
+        // Send presence data every 10 seconds
+        this.set('keepAliveTimer', Ember.run.later(this, 'keepPresenceAlive', 10000));
+      }
+    },
+
+
+
+    keepPresenceAlive(){
+      // If the composer isn't open, or we're not editing, 
+      // don't update anything, and don't schedule this task again
+      if(!this.shouldSharePresence()){
+        return;
+      }
+
+      // Only send the keepalive message if the browser has focus
+      if(pageVisible()){
+        ajax('/presence/publish/', {
+          type: 'POST',
+          data: { current: this.get('presenceState') }
+        }).catch((error) => {
+          // This isn't a critical failure, so don't disturb the user
+          console.error("Error publishing composer status", error);
+        });
+      }
+
+      // Schedule again in another 30 seconds
+      Ember.run.cancel(this.get('keepAliveTimer'));
+      this.set('keepAliveTimer', Ember.run.later(this, 'keepPresenceAlive', 10000));
+    }
+
+  });
+}
+
+export default {
+  name: "composer-controller-presence",
+  after: "message-bus",
+
+  initialize(container) {
+    const siteSettings = container.lookup('site-settings:main');
+    if (siteSettings.presence_enabled) withPluginApi('0.8.9', initialize);
+  }
+};
diff --git a/plugins/discourse-presence/assets/javascripts/discourse/templates/components/composer-presence-display.hbs b/plugins/discourse-presence/assets/javascripts/discourse/templates/components/composer-presence-display.hbs
new file mode 100644
index 00000000000..1b105bcd817
--- /dev/null
+++ b/plugins/discourse-presence/assets/javascripts/discourse/templates/components/composer-presence-display.hbs
@@ -0,0 +1,18 @@
+{{#if shouldDisplay}}
+  <div class="presence-users">
+    {{#each users as |user|}}
+      {{avatar user avatarTemplatePath="avatar_template" usernamePath="username" imageSize="small"}}
+    {{/each}}
+
+    <span class="presence_text">
+      <span class="description">
+        {{#if isReply ~}}
+          {{i18n 'presence.is_replying' count=users.length}}
+        {{~else~}}
+          {{i18n 'presence.is_editing' count=users.length}}
+        {{~/if}}</span>{{!-- (using comment to stop whitespace)
+   --}}</span>{{!--
+   --}}<span class="wave"><span class="dot">.</span><span class="dot">.</span><span class="dot">.</span>
+    </span>
+  </div>
+{{/if}}
\ No newline at end of file
diff --git a/plugins/discourse-presence/assets/javascripts/discourse/templates/connectors/composer-fields/presence.hbs b/plugins/discourse-presence/assets/javascripts/discourse/templates/connectors/composer-fields/presence.hbs
new file mode 100644
index 00000000000..0f3c2e1b95b
--- /dev/null
+++ b/plugins/discourse-presence/assets/javascripts/discourse/templates/connectors/composer-fields/presence.hbs
@@ -0,0 +1,3 @@
+{{#if siteSettings.presence_enabled}}
+  {{composer-presence-display}}
+{{/if}}
diff --git a/plugins/discourse-presence/assets/stylesheets/presence.scss b/plugins/discourse-presence/assets/stylesheets/presence.scss
new file mode 100644
index 00000000000..7b2c04c466c
--- /dev/null
+++ b/plugins/discourse-presence/assets/stylesheets/presence.scss
@@ -0,0 +1,45 @@
+.presence-users{
+  
+  background-color: $primary-low;
+
+  color: $primary-medium;
+  padding: 0px 5px;
+  position: absolute;
+  top: 8px;
+  right: 30px;
+
+
+  .wave {
+
+    .dot {
+      display: inline-block;
+      animation: wave 1.8s linear infinite;
+
+      &:nth-child(2) {
+        animation-delay: -1.6s;
+      }
+
+      &:nth-child(3) {
+        animation-delay: -1.4s;
+      }
+    }
+  }
+
+  @keyframes wave {
+    0%, 60%, 100% {
+      transform: initial;
+    }
+
+    30% {
+      transform: translateY(-0.2em);
+    }
+  }
+}
+
+.mobile-view .presence-users{
+  top: 5px;
+  right: 60px;
+  .description{
+    display:none;
+  }
+}
\ No newline at end of file
diff --git a/plugins/discourse-presence/config/locales/client.en.yml b/plugins/discourse-presence/config/locales/client.en.yml
new file mode 100644
index 00000000000..9de83306d75
--- /dev/null
+++ b/plugins/discourse-presence/config/locales/client.en.yml
@@ -0,0 +1,9 @@
+en:
+  js:
+    presence:
+      is_replying: 
+        one: "is also replying"
+        other: "are also replying"
+      is_editing: 
+        one: "is also editing"
+        other: "are also editing"
\ No newline at end of file
diff --git a/plugins/discourse-presence/config/locales/server.en.yml b/plugins/discourse-presence/config/locales/server.en.yml
new file mode 100644
index 00000000000..72768d3f25f
--- /dev/null
+++ b/plugins/discourse-presence/config/locales/server.en.yml
@@ -0,0 +1,3 @@
+en:
+  site_settings:
+    presence_enabled: 'Show users that are currently replying to the current topic, or editing the current post?'
diff --git a/plugins/discourse-presence/config/settings.yml b/plugins/discourse-presence/config/settings.yml
new file mode 100644
index 00000000000..0bc0899aa8a
--- /dev/null
+++ b/plugins/discourse-presence/config/settings.yml
@@ -0,0 +1,4 @@
+plugins:
+  presence_enabled:
+    default: true
+    client: true
\ No newline at end of file
diff --git a/plugins/discourse-presence/plugin.rb b/plugins/discourse-presence/plugin.rb
new file mode 100644
index 00000000000..9ee7a498470
--- /dev/null
+++ b/plugins/discourse-presence/plugin.rb
@@ -0,0 +1,148 @@
+# name: discourse-presence
+# about: Show which users are writing a reply to a topic
+# version: 1.0
+# authors: André Pereira, David Taylor
+# url: https://github.com/discourse/discourse-presence.git
+
+enabled_site_setting :presence_enabled
+
+register_asset 'stylesheets/presence.scss'
+
+PLUGIN_NAME ||= "discourse-presence".freeze
+
+after_initialize do
+
+  module ::Presence
+    class Engine < ::Rails::Engine
+      engine_name PLUGIN_NAME
+      isolate_namespace Presence
+    end
+  end
+
+  module ::Presence::PresenceManager
+    def self.get_redis_key(type, id)
+      "presence:#{type}:#{id}"
+    end
+
+    def self.get_messagebus_channel(type, id)
+      "/presence/#{type}/#{id}"
+    end
+
+    def self.add(type, id, user_id)
+      redis_key = get_redis_key(type, id)
+      response = $redis.hset(redis_key, user_id, Time.zone.now)
+
+      response # Will be true if a new key
+    end
+
+    def self.remove(type, id, user_id)
+      redis_key = get_redis_key(type, id)
+      response = $redis.hdel(redis_key, user_id)
+
+      response > 0 # Return true if key was actually deleted
+    end
+
+    def self.get_users(type, id)
+      redis_key = get_redis_key(type, id)
+      user_ids = $redis.hkeys(redis_key).map(&:to_i)
+
+      User.where(id: user_ids)
+    end
+
+    def self.publish(type, id)
+      users = get_users(type, id)
+      serialized_users = users.map { |u| BasicUserSerializer.new(u, root: false) }
+      message = {
+        users: serialized_users
+      }
+      MessageBus.publish(get_messagebus_channel(type, id), message.as_json)
+
+      users
+    end
+
+    def self.cleanup(type, id)
+      hash = $redis.hgetall(get_redis_key(type, id))
+      original_hash_size = hash.length
+
+      any_changes = false
+
+      # Delete entries older than 20 seconds
+      hash.each do |user_id, time|
+        if Time.zone.now - Time.parse(time) >= 20
+          any_changes ||= remove(type, id, user_id)
+        end
+      end
+
+      any_changes
+    end
+
+  end
+
+  require_dependency "application_controller"
+
+  class Presence::PresencesController < ::ApplicationController
+    before_filter :ensure_logged_in
+
+    def publish
+      data = params.permit(:response_needed,
+              current: [:compose_state, :action, :topic_id, :post_id],
+              previous: [:compose_state, :action, :topic_id, :post_id]
+              )
+
+      if data[:previous] &&
+          data[:previous][:compose_state] == 'open' &&
+          data[:previous][:action].in?(['edit', 'reply'])
+
+        type = data[:previous][:post_id] ? 'post' : 'topic'
+        id = data[:previous][:post_id] ? data[:previous][:post_id] : data[:previous][:topic_id]
+
+        any_changes = false
+        any_changes ||= Presence::PresenceManager.remove(type, id, current_user.id)
+        any_changes ||= Presence::PresenceManager.cleanup(type, id)
+
+        users = Presence::PresenceManager.publish(type, id) if any_changes
+      end
+
+      if data[:current] &&
+          data[:current][:compose_state] == 'open' &&
+          data[:current][:action].in?(['edit', 'reply'])
+
+        type = data[:current][:post_id] ? 'post' : 'topic'
+        id = data[:current][:post_id] ? data[:current][:post_id] : data[:current][:topic_id]
+
+        any_changes = false
+        any_changes ||= Presence::PresenceManager.add(type, id, current_user.id)
+        any_changes ||= Presence::PresenceManager.cleanup(type, id)
+
+        users = Presence::PresenceManager.publish(type, id) if any_changes
+
+        if data[:response_needed]
+          users ||= Presence::PresenceManager.get_users(type, id)
+
+          serialized_users = users.map { |u| BasicUserSerializer.new(u, root: false) }
+
+          messagebus_channel = Presence::PresenceManager.get_messagebus_channel(type, id)
+
+          render json: {
+            messagebus_channel: messagebus_channel,
+            messagebus_id: MessageBus.last_id(messagebus_channel),
+            users: serialized_users
+          }
+          return
+        end
+      end
+
+      render json: {}
+    end
+
+  end
+
+  Presence::Engine.routes.draw do
+    post '/publish' => 'presences#publish'
+  end
+
+  Discourse::Application.routes.append do
+    mount ::Presence::Engine, at: '/presence'
+  end
+
+end
diff --git a/plugins/discourse-presence/spec/presence_controller_spec.rb b/plugins/discourse-presence/spec/presence_controller_spec.rb
new file mode 100644
index 00000000000..c15263714e2
--- /dev/null
+++ b/plugins/discourse-presence/spec/presence_controller_spec.rb
@@ -0,0 +1,80 @@
+require 'rails_helper'
+
+describe ::Presence::PresencesController, type: :request do
+
+  before do
+    SiteSetting.presence_enabled = true
+  end
+
+  let(:user1) { Fabricate(:user) }
+  let(:user2) { Fabricate(:user) }
+  let(:user3) { Fabricate(:user) }
+
+  after(:each) do
+    $redis.del('presence:post:22')
+    $redis.del('presence:post:11')
+  end
+
+  context 'when not logged in' do
+    it 'should raise the right error' do
+      expect { post '/presence/publish.json' }.to raise_error(Discourse::NotLoggedIn)
+    end
+  end
+
+  context 'when logged in' do
+    before do
+      sign_in(user1)
+    end
+
+    it "doesn't produce an error" do
+      expect { post '/presence/publish.json' }.not_to raise_error
+    end
+
+    it "returns a response when requested" do
+      messages = MessageBus.track_publish do
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 22 }, response_needed: true
+      end
+
+      expect(messages.count).to eq (1)
+
+      data = JSON.parse(response.body)
+
+      expect(data['messagebus_channel']).to eq('/presence/post/22')
+      expect(data['messagebus_id']).to eq(MessageBus.last_id('/presence/post/22'))
+      expect(data['users'][0]["id"]).to eq(user1.id)
+    end
+
+    it "doesn't return a response when not requested" do
+      messages = MessageBus.track_publish do
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 22 }
+      end
+
+      expect(messages.count).to eq (1)
+
+      data = JSON.parse(response.body)
+      expect(data).to eq({})
+    end
+
+    it "doesn't send duplicate messagebus messages" do
+      messages = MessageBus.track_publish do
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 22 }
+      end
+      expect(messages.count).to eq (1)
+
+      messages = MessageBus.track_publish do
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 22 }
+      end
+      expect(messages.count).to eq (0)
+    end
+
+    it "clears 'previous' state when supplied" do
+      messages = MessageBus.track_publish do
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 22 }
+        post '/presence/publish.json', current: { compose_state: 'open', action: 'edit', post_id: 11 }, previous: { compose_state: 'open', action: 'edit', post_id: 22 }
+      end
+      expect(messages.count).to eq (3)
+    end
+
+  end
+
+end
diff --git a/plugins/discourse-presence/spec/presence_manager_spec.rb b/plugins/discourse-presence/spec/presence_manager_spec.rb
new file mode 100644
index 00000000000..0c98197a474
--- /dev/null
+++ b/plugins/discourse-presence/spec/presence_manager_spec.rb
@@ -0,0 +1,64 @@
+require 'rails_helper'
+
+describe ::Presence::PresenceManager do
+
+  let(:user1) { Fabricate(:user) }
+  let(:user2) { Fabricate(:user) }
+  let(:user3) { Fabricate(:user) }
+  let(:manager) { ::Presence::PresenceManager }
+
+  after(:each) do
+    $redis.del('presence:post:22')
+    $redis.del('presence:post:11')
+  end
+
+  it 'adds, removes and lists users correctly' do
+    expect(manager.get_users('post', 22).count).to eq(0)
+
+    expect(manager.add('post', 22, user1.id)).to be true
+    expect(manager.add('post', 22, user2.id)).to be true
+    expect(manager.add('post', 11, user3.id)).to be true
+
+    expect(manager.get_users('post', 22).count).to eq(2)
+    expect(manager.get_users('post', 11).count).to eq(1)
+
+    expect(manager.get_users('post', 22)).to contain_exactly(user1, user2)
+    expect(manager.get_users('post', 11)).to contain_exactly(user3)
+
+    expect(manager.remove('post', 22, user1.id)).to be true
+    expect(manager.get_users('post', 22).count).to eq(1)
+    expect(manager.get_users('post', 22)).to contain_exactly(user2)
+  end
+
+  it 'publishes correctly' do
+    expect(manager.get_users('post', 22).count).to eq(0)
+
+    manager.add('post', 22, user1.id)
+    manager.add('post', 22, user2.id)
+
+    messages = MessageBus.track_publish do
+      manager.publish('post', 22)
+    end
+
+    expect(messages.count).to eq (1)
+    message = messages.first
+
+    expect(message.channel).to eq('/presence/post/22')
+
+    expect(message.data["users"].map { |u| u[:id] }).to contain_exactly(user1.id, user2.id)
+  end
+
+  it 'cleans up correctly' do
+    freeze_time Time.zone.now do
+      expect(manager.add('post', 22, user1.id)).to be true
+      expect(manager.cleanup('post', 22)).to be false # Nothing to cleanup
+      expect(manager.get_users('post', 22).count).to eq(1)
+    end
+
+    # Anything older than 20 seconds should be cleaned up
+    freeze_time 30.seconds.from_now do
+      expect(manager.cleanup('post', 22)).to be true
+      expect(manager.get_users('post', 22).count).to eq(0)
+    end
+  end
+end