diff --git a/app/assets/javascripts/discourse/app/components/popup-input-tip.js b/app/assets/javascripts/discourse/app/components/popup-input-tip.js
index 8508a7e7610..a119210a6e9 100644
--- a/app/assets/javascripts/discourse/app/components/popup-input-tip.js
+++ b/app/assets/javascripts/discourse/app/components/popup-input-tip.js
@@ -1,10 +1,11 @@
 import { not, or, reads } from "@ember/object/computed";
 import discourseComputed from "discourse-common/utils/decorators";
 import Component from "@ember/component";
-import { getOwner } from "discourse-common/lib/get-owner";
 import { htmlSafe } from "@ember/template";
+import { inject as service } from "@ember/service";
 
 export default Component.extend({
+  composer: service(),
   tagName: "a",
   classNameBindings: [":popup-tip", "good", "bad", "lastShownAt::hide"],
   attributeBindings: ["role", "ariaLabel", "tabindex"],
@@ -28,8 +29,7 @@ export default Component.extend({
 
   dismiss() {
     this.set("shownAt", null);
-    const composer = getOwner(this).lookup("controller:composer");
-    composer.clearLastValidatedAt();
+    this.composer.clearLastValidatedAt();
     this.element.previousElementSibling?.focus();
   },
 
diff --git a/app/assets/javascripts/discourse/app/components/sidebar/user/community-section.js b/app/assets/javascripts/discourse/app/components/sidebar/user/community-section.js
index 2bcb92da48d..99964a082d9 100644
--- a/app/assets/javascripts/discourse/app/components/sidebar/user/community-section.js
+++ b/app/assets/javascripts/discourse/app/components/sidebar/user/community-section.js
@@ -16,8 +16,11 @@ import SidebarCommonCommunitySection from "discourse/components/sidebar/common/c
 
 import { action } from "@ember/object";
 import { next } from "@ember/runloop";
+import { inject as service } from "@ember/service";
 
 export default class SidebarUserCommunitySection extends SidebarCommonCommunitySection {
+  @service composer;
+
   constructor() {
     super(...arguments);
 
@@ -68,7 +71,7 @@ export default class SidebarUserCommunitySection extends SidebarCommonCommunityS
     }
 
     next(() => {
-      getOwner(this).lookup("controller:composer").open(composerArgs);
+      this.composer.open(composerArgs);
     });
   }
 }
diff --git a/app/assets/javascripts/discourse/app/components/user-stream.js b/app/assets/javascripts/discourse/app/components/user-stream.js
index d025570b456..b6aa0dd839c 100644
--- a/app/assets/javascripts/discourse/app/components/user-stream.js
+++ b/app/assets/javascripts/discourse/app/components/user-stream.js
@@ -6,7 +6,6 @@ import I18n from "I18n";
 import LoadMore from "discourse/mixins/load-more";
 import Post from "discourse/models/post";
 import { NEW_TOPIC_KEY } from "discourse/models/composer";
-import { getOwner } from "discourse-common/lib/get-owner";
 import { observes } from "discourse-common/utils/decorators";
 import { on } from "@ember/object/evented";
 import { popupAjaxError } from "discourse/lib/ajax-error";
@@ -16,6 +15,7 @@ import { inject as service } from "@ember/service";
 export default Component.extend(LoadMore, {
   tagName: "ul",
   dialog: service(),
+  composer: service(),
   _lastDecoratedElement: null,
 
   _initialize: on("init", function () {
@@ -100,9 +100,8 @@ export default Component.extend(LoadMore, {
     },
 
     resumeDraft(item) {
-      const composer = getOwner(this).lookup("controller:composer");
-      if (composer.get("model.viewOpen")) {
-        composer.close();
+      if (this.composer.get("model.viewOpen")) {
+        this.composer.close();
       }
       if (item.get("postUrl")) {
         DiscourseURL.routeTo(item.get("postUrl"));
@@ -114,7 +113,7 @@ export default Component.extend(LoadMore, {
               return;
             }
 
-            composer.open({
+            this.composer.open({
               draft,
               draftKey: item.draft_key,
               draftSequence: d.draft_sequence,
diff --git a/app/assets/javascripts/discourse/app/controllers/full-page-search.js b/app/assets/javascripts/discourse/app/controllers/full-page-search.js
index e27ce685fb8..519b9ff0669 100644
--- a/app/assets/javascripts/discourse/app/controllers/full-page-search.js
+++ b/app/assets/javascripts/discourse/app/controllers/full-page-search.js
@@ -22,6 +22,7 @@ import { Promise } from "rsvp";
 import { search as searchCategoryTag } from "discourse/lib/category-tag-search";
 import showModal from "discourse/lib/show-modal";
 import userSearch from "discourse/lib/user-search";
+import { inject as service } from "@ember/service";
 
 const SortOrders = [
   { name: I18n.t("search.relevance"), id: 0 },
@@ -49,7 +50,7 @@ export function registerFullPageSearchType(
 
 export default Controller.extend({
   application: controller(),
-  composer: controller(),
+  composer: service(),
   bulkSelectEnabled: null,
 
   loading: false,
diff --git a/app/assets/javascripts/discourse/app/controllers/topic.js b/app/assets/javascripts/discourse/app/controllers/topic.js
index 78e72ab5044..3a097c334ac 100644
--- a/app/assets/javascripts/discourse/app/controllers/topic.js
+++ b/app/assets/javascripts/discourse/app/controllers/topic.js
@@ -47,7 +47,7 @@ export function registerCustomPostMessageCallback(type, callback) {
 }
 
 export default Controller.extend(bufferedProperty("model"), {
-  composer: controller(),
+  composer: service(),
   application: controller(),
   dialog: service(),
   documentTitle: service(),
diff --git a/app/assets/javascripts/discourse/app/lib/keyboard-shortcuts.js b/app/assets/javascripts/discourse/app/lib/keyboard-shortcuts.js
index e5b75854665..909d0ec1d11 100644
--- a/app/assets/javascripts/discourse/app/lib/keyboard-shortcuts.js
+++ b/app/assets/javascripts/discourse/app/lib/keyboard-shortcuts.js
@@ -445,14 +445,14 @@ export default {
       return;
     }
 
-    this.container.lookup("controller:composer").open({
+    this.container.lookup("service:composer").open({
       action: Composer.CREATE_TOPIC,
       draftKey: Composer.NEW_TOPIC_KEY,
     });
   },
 
   focusComposer(event) {
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     if (event) {
       event.preventDefault();
       event.stopPropagation();
@@ -461,7 +461,7 @@ export default {
   },
 
   fullscreenComposer() {
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     if (composer.get("model")) {
       composer.toggleFullscreen();
     }
diff --git a/app/assets/javascripts/discourse/app/lib/plugin-api.js b/app/assets/javascripts/discourse/app/lib/plugin-api.js
index ed2ca159f1b..9d5c128de78 100644
--- a/app/assets/javascripts/discourse/app/lib/plugin-api.js
+++ b/app/assets/javascripts/discourse/app/lib/plugin-api.js
@@ -58,7 +58,7 @@ import { addPluginReviewableParam } from "discourse/components/reviewable-item";
 import {
   addComposerSaveErrorCallback,
   addPopupMenuOptionsCallback,
-} from "discourse/controllers/composer";
+} from "discourse/services/composer";
 import { addPostClassesCallback } from "discourse/widgets/post";
 import {
   addGroupPostSmallActionCode,
diff --git a/app/assets/javascripts/discourse/app/lib/url.js b/app/assets/javascripts/discourse/app/lib/url.js
index f7d7eb89bd7..b2a4046388a 100644
--- a/app/assets/javascripts/discourse/app/lib/url.js
+++ b/app/assets/javascripts/discourse/app/lib/url.js
@@ -409,7 +409,7 @@ const DiscourseURL = EmberObject.extend({
   },
 
   get isComposerOpen() {
-    return this.controllerFor("composer")?.visible;
+    return this.container.lookup("service:composer")?.visible;
   },
 
   get router() {
diff --git a/app/assets/javascripts/discourse/app/mixins/open-composer.js b/app/assets/javascripts/discourse/app/mixins/open-composer.js
index c5e58c52ad4..1e06c9cf396 100644
--- a/app/assets/javascripts/discourse/app/mixins/open-composer.js
+++ b/app/assets/javascripts/discourse/app/mixins/open-composer.js
@@ -1,6 +1,7 @@
 // This mixin allows a route to open the composer
 import Composer from "discourse/models/composer";
 import Mixin from "@ember/object/mixin";
+import { getOwner } from "discourse-common/lib/get-owner";
 
 export default Mixin.create({
   openComposer(controller) {
@@ -13,13 +14,15 @@ export default Mixin.create({
       categoryId = null;
     }
 
-    this.controllerFor("composer").open({
-      prioritizedCategoryId: categoryId,
-      topicCategoryId: categoryId,
-      action: Composer.CREATE_TOPIC,
-      draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
-      draftSequence: controller.get("model.draft_sequence") || 0,
-    });
+    getOwner(this)
+      .lookup("service:composer")
+      .open({
+        prioritizedCategoryId: categoryId,
+        topicCategoryId: categoryId,
+        action: Composer.CREATE_TOPIC,
+        draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
+        draftSequence: controller.get("model.draft_sequence") || 0,
+      });
   },
 
   openComposerWithTopicParams(
@@ -29,15 +32,17 @@ export default Mixin.create({
     topicCategoryId,
     topicTags
   ) {
-    this.controllerFor("composer").open({
-      action: Composer.CREATE_TOPIC,
-      topicTitle,
-      topicBody,
-      topicCategoryId,
-      topicTags,
-      draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
-      draftSequence: controller.get("model.draft_sequence"),
-    });
+    getOwner(this)
+      .lookup("service:composer")
+      .open({
+        action: Composer.CREATE_TOPIC,
+        topicTitle,
+        topicBody,
+        topicCategoryId,
+        topicTags,
+        draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
+        draftSequence: controller.get("model.draft_sequence"),
+      });
   },
 
   openComposerWithMessageParams({
@@ -46,7 +51,7 @@ export default Mixin.create({
     topicBody = "",
     hasGroups = false,
   } = {}) {
-    this.controllerFor("composer").open({
+    getOwner(this).lookup("service:composer").open({
       action: Composer.PRIVATE_MESSAGE,
       recipients,
       topicTitle,
diff --git a/app/assets/javascripts/discourse/app/routes/application.js b/app/assets/javascripts/discourse/app/routes/application.js
index 0f612eeb46e..317efa6ca52 100644
--- a/app/assets/javascripts/discourse/app/routes/application.js
+++ b/app/assets/javascripts/discourse/app/routes/application.js
@@ -39,6 +39,7 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
   shortSiteDescription: setting("short_site_description"),
   documentTitle: service(),
   dialog: service(),
+  composer: service(),
 
   actions: {
     toggleAnonymous() {
@@ -84,7 +85,7 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
         : null;
 
       // used only once, one less dependency
-      return this.controllerFor("composer").open({
+      return this.composer.open({
         action: Composer.PRIVATE_MESSAGE,
         recipients,
         archetypeId: "private_message",
diff --git a/app/assets/javascripts/discourse/app/routes/build-category-route.js b/app/assets/javascripts/discourse/app/routes/build-category-route.js
index df3061caa42..9134bc71947 100644
--- a/app/assets/javascripts/discourse/app/routes/build-category-route.js
+++ b/app/assets/javascripts/discourse/app/routes/build-category-route.js
@@ -16,11 +16,13 @@ import PermissionType from "discourse/models/permission-type";
 import TopicList from "discourse/models/topic-list";
 import { action } from "@ember/object";
 import PreloadStore from "discourse/lib/preload-store";
+import { inject as service } from "@ember/service";
 
 // A helper function to create a category route with parameters
 export default (filterArg, params) => {
   return DiscourseRoute.extend({
     queryParams,
+    composer: service(),
 
     model(modelParams) {
       const category = Category.findBySlugPathWithID(
@@ -209,7 +211,7 @@ export default (filterArg, params) => {
     deactivate() {
       this._super(...arguments);
 
-      this.controllerFor("composer").set("prioritizedCategoryId", null);
+      this.composer.set("prioritizedCategoryId", null);
       this.searchService.set("searchContext", null);
     },
 
diff --git a/app/assets/javascripts/discourse/app/routes/discourse.js b/app/assets/javascripts/discourse/app/routes/discourse.js
index fc9792da024..9b2f976c5c7 100644
--- a/app/assets/javascripts/discourse/app/routes/discourse.js
+++ b/app/assets/javascripts/discourse/app/routes/discourse.js
@@ -3,6 +3,7 @@ import Draft from "discourse/models/draft";
 import Route from "@ember/routing/route";
 import { once } from "@ember/runloop";
 import { seenUser } from "discourse/lib/user-presence";
+import { getOwner } from "discourse-common/lib/get-owner";
 
 const DiscourseRoute = Route.extend({
   showFooter: false,
@@ -53,7 +54,7 @@ const DiscourseRoute = Route.extend({
   },
 
   openTopicDraft() {
-    const composer = this.controllerFor("composer");
+    const composer = getOwner(this).lookup("service:composer");
 
     if (
       composer.get("model.action") === Composer.CREATE_TOPIC &&
diff --git a/app/assets/javascripts/discourse/app/routes/tag-show.js b/app/assets/javascripts/discourse/app/routes/tag-show.js
index dfdcf3aa29d..8d3d00eb13c 100644
--- a/app/assets/javascripts/discourse/app/routes/tag-show.js
+++ b/app/assets/javascripts/discourse/app/routes/tag-show.js
@@ -18,11 +18,13 @@ import { setTopicList } from "discourse/lib/topic-list-tracker";
 import showModal from "discourse/lib/show-modal";
 import { action } from "@ember/object";
 import PreloadStore from "discourse/lib/preload-store";
+import { inject as service } from "@ember/service";
 
 const NONE = "none";
 const ALL = "all";
 
 export default DiscourseRoute.extend(FilterModeMixin, {
+  composer: service(),
   navMode: "latest",
 
   queryParams,
@@ -214,8 +216,7 @@ export default DiscourseRoute.extend(FilterModeMixin, {
       this.openTopicDraft();
     } else {
       const controller = this.controllerFor("tag.show");
-      const composerController = this.controllerFor("composer");
-      composerController
+      this.composer
         .open({
           categoryId: controller.category?.id,
           action: Composer.CREATE_TOPIC,
@@ -223,8 +224,8 @@ export default DiscourseRoute.extend(FilterModeMixin, {
         })
         .then(() => {
           // Pre-fill the tags input field
-          if (composerController.canEditTags && controller.tag?.id) {
-            const composerModel = this.controllerFor("composer").model;
+          if (this.composer.canEditTags && controller.tag?.id) {
+            const composerModel = this.composer.model;
             composerModel.set("tags", this._controllerTags(controller));
           }
         });
diff --git a/app/assets/javascripts/discourse/app/routes/topic-from-params.js b/app/assets/javascripts/discourse/app/routes/topic-from-params.js
index 5875089d6d7..2f5f6334d84 100644
--- a/app/assets/javascripts/discourse/app/routes/topic-from-params.js
+++ b/app/assets/javascripts/discourse/app/routes/topic-from-params.js
@@ -5,9 +5,12 @@ import { isEmpty } from "@ember/utils";
 import { isTesting } from "discourse-common/config/environment";
 import { schedule } from "@ember/runloop";
 import { action } from "@ember/object";
+import { inject as service } from "@ember/service";
 
 // This route is used for retrieving a topic based on params
 export default DiscourseRoute.extend({
+  composer: service(),
+
   // Avoid default model hook
   model(params) {
     params = params || {};
@@ -56,7 +59,6 @@ export default DiscourseRoute.extend({
     }
 
     const topicController = this.controllerFor("topic");
-    const composerController = this.controllerFor("composer");
     const topic = this.modelFor("topic");
     const postStream = topic.postStream;
 
@@ -105,7 +107,7 @@ export default DiscourseRoute.extend({
     }
 
     if (!isEmpty(topic.draft)) {
-      composerController.open({
+      this.composer.open({
         draft: Draft.getLocal(topic.draft_key, topic.draft),
         draftKey: topic.draft_key,
         draftSequence: topic.draft_sequence,
diff --git a/app/assets/javascripts/discourse/app/routes/topic.js b/app/assets/javascripts/discourse/app/routes/topic.js
index fcb14b14673..861ad01e0f9 100644
--- a/app/assets/javascripts/discourse/app/routes/topic.js
+++ b/app/assets/javascripts/discourse/app/routes/topic.js
@@ -14,6 +14,7 @@ import PostFlag from "discourse/lib/flag-targets/post-flag";
 const SCROLL_DELAY = 500;
 
 const TopicRoute = DiscourseRoute.extend({
+  composer: service(),
   screenTrack: service(),
 
   scheduledReplace: null,
@@ -332,7 +333,7 @@ const TopicRoute = DiscourseRoute.extend({
     postStream.cancelFilter();
 
     topicController.set("multiSelect", false);
-    this.controllerFor("composer").set("topic", null);
+    this.composer.set("topic", null);
     this.screenTrack.stop();
 
     this.appEvents.trigger("header:hide-topic");
@@ -356,7 +357,7 @@ const TopicRoute = DiscourseRoute.extend({
     controller.set("multiSelect", false);
     controller.get("quoteState").clear();
 
-    this.controllerFor("composer").set("topic", model);
+    this.composer.set("topic", model);
     this.topicTrackingState.trackIncoming("all");
 
     // We reset screen tracking every time a topic is entered
diff --git a/app/assets/javascripts/discourse/app/routes/user-private-messages.js b/app/assets/javascripts/discourse/app/routes/user-private-messages.js
index 319cc1caad8..5e631ce9ac8 100644
--- a/app/assets/javascripts/discourse/app/routes/user-private-messages.js
+++ b/app/assets/javascripts/discourse/app/routes/user-private-messages.js
@@ -2,8 +2,11 @@ import Composer from "discourse/models/composer";
 import DiscourseRoute from "discourse/routes/discourse";
 import Draft from "discourse/models/draft";
 import { action } from "@ember/object";
+import { inject as service } from "@ember/service";
 
 export default DiscourseRoute.extend({
+  composer: service(),
+
   renderTemplate() {
     this.render("user/messages");
   },
@@ -20,11 +23,9 @@ export default DiscourseRoute.extend({
     controller.set("model", model);
 
     if (this.currentUser) {
-      const composerController = this.controllerFor("composer");
-
       Draft.get("new_private_message").then((data) => {
         if (data.draft) {
-          composerController.open({
+          this.composer.open({
             draft: data.draft,
             draftKey: Composer.NEW_PRIVATE_MESSAGE_KEY,
             ignoreIfChanged: true,
diff --git a/app/assets/javascripts/discourse/tests/acceptance/composer-actions-test.js b/app/assets/javascripts/discourse/tests/acceptance/composer-actions-test.js
index dcd0adea595..3e126039f9b 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/composer-actions-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/composer-actions-test.js
@@ -12,7 +12,7 @@ import I18n from "I18n";
 import selectKit from "discourse/tests/helpers/select-kit-helper";
 import sinon from "sinon";
 import { test } from "qunit";
-import { toggleCheckDraftPopup } from "discourse/controllers/composer";
+import { toggleCheckDraftPopup } from "discourse/services/composer";
 import userFixtures from "discourse/tests/fixtures/user-fixtures";
 import { cloneJSON } from "discourse-common/lib/object";
 
diff --git a/app/assets/javascripts/discourse/tests/acceptance/composer-test.js b/app/assets/javascripts/discourse/tests/acceptance/composer-test.js
index d021bd1c9e5..0638c39aae4 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/composer-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/composer-test.js
@@ -7,7 +7,7 @@ import {
   triggerKeyEvent,
   visit,
 } from "@ember/test-helpers";
-import { toggleCheckDraftPopup } from "discourse/controllers/composer";
+import { toggleCheckDraftPopup } from "discourse/services/composer";
 import { cloneJSON } from "discourse-common/lib/object";
 import TopicFixtures from "discourse/tests/fixtures/topic";
 import LinkLookup from "discourse/lib/link-lookup";
@@ -1016,7 +1016,7 @@ acceptance("Composer", function (needs) {
     await visit("/t/internationalization-localization/280");
     await click("#topic-footer-buttons .create");
 
-    this.container.lookup("controller:composer").set(
+    this.container.lookup("service:composer").set(
       "linkLookup",
       new LinkLookup({
         "github.com": {
@@ -1185,7 +1185,7 @@ acceptance("Composer - Focus Open and Closed", function (needs) {
   test("Focusing a composer which is not open with create topic", async function (assert) {
     await visit("/t/internationalization-localization/280");
 
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     await composer.focusComposer({ fallbackToNewTopic: true });
 
     await settled();
@@ -1200,7 +1200,7 @@ acceptance("Composer - Focus Open and Closed", function (needs) {
   test("Focusing a composer which is not open with create topic and append text", async function (assert) {
     await visit("/t/internationalization-localization/280");
 
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     await composer.focusComposer({
       fallbackToNewTopic: true,
       insertText: "this is appended",
@@ -1222,7 +1222,7 @@ acceptance("Composer - Focus Open and Closed", function (needs) {
     await visit("/");
     await click("#create-topic");
 
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     await composer.focusComposer();
 
     await settled();
@@ -1237,7 +1237,7 @@ acceptance("Composer - Focus Open and Closed", function (needs) {
     await visit("/");
     await click("#create-topic");
 
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     await composer.focusComposer({ insertText: "this is some appended text" });
 
     await settled();
@@ -1259,7 +1259,7 @@ acceptance("Composer - Focus Open and Closed", function (needs) {
     await fillIn(".d-editor-input", "This is a dirty reply");
     await click(".toggle-minimize");
 
-    const composer = this.container.lookup("controller:composer");
+    const composer = this.container.lookup("service:composer");
     await composer.focusComposer({ insertText: "this is some appended text" });
 
     await settled();
diff --git a/app/assets/javascripts/discourse/tests/acceptance/tags-test.js b/app/assets/javascripts/discourse/tests/acceptance/tags-test.js
index cfeb1b29446..f7db49b9f4b 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/tags-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/tags-test.js
@@ -542,7 +542,7 @@ acceptance("Tag info", function (needs) {
   test("composer will not set tags if user cannot create them", async function (assert) {
     await visit("/tag/planters");
     await click("#create-topic");
-    let composer = this.owner.lookup("controller:composer");
+    let composer = this.owner.lookup("service:composer");
     assert.strictEqual(composer.get("model").tags, undefined);
   });
 });
@@ -611,7 +611,7 @@ acceptance("Tag show - create topic", function (needs) {
   });
 
   test("composer will not set tags with all/none tags when creating topic", async function (assert) {
-    const composer = this.owner.lookup("controller:composer");
+    const composer = this.owner.lookup("service:composer");
 
     await visit("/tag/none");
     await click("#create-topic");
@@ -623,7 +623,7 @@ acceptance("Tag show - create topic", function (needs) {
   });
 
   test("composer will set tags from selected tag", async function (assert) {
-    const composer = this.owner.lookup("controller:composer");
+    const composer = this.owner.lookup("service:composer");
 
     await visit("/tag/planters");
     await click("#create-topic");