diff --git a/.changeset/metal-garlics-fetch.md b/.changeset/metal-garlics-fetch.md
new file mode 100644
index 0000000000..076b5f34a5
--- /dev/null
+++ b/.changeset/metal-garlics-fetch.md
@@ -0,0 +1,6 @@
+---
+'@backstage/frontend-plugin-api': patch
+'@backstage/frontend-app-api': patch
+---
+
+Moved several implementations of built-in APIs from being hardcoded in the app to instead be provided as API extensions. This moves all API-related inputs from the `app` extension to the respective API extensions. For example, extensions created with `ThemeBlueprint` are now attached to the `themes` input of `api:app-theme` rather than the `app` extension.
diff --git a/.changeset/yellow-bees-hope.md b/.changeset/yellow-bees-hope.md
new file mode 100644
index 0000000000..1ea8690c20
--- /dev/null
+++ b/.changeset/yellow-bees-hope.md
@@ -0,0 +1,5 @@
+---
+'@backstage/frontend-app-api': minor
+---
+
+Removed deprecated `icons` property passing to `createApp` and `createSpecializedApp`. Use `IconBundleBlueprint.make` to create extensions instead and include them in the app.
diff --git a/packages/frontend-app-api/api-report.md b/packages/frontend-app-api/api-report.md
index 27d486b6a8..c837ff09b7 100644
--- a/packages/frontend-app-api/api-report.md
+++ b/packages/frontend-app-api/api-report.md
@@ -6,7 +6,6 @@
 import { ConfigApi } from '@backstage/core-plugin-api';
 import { ExternalRouteRef } from '@backstage/frontend-plugin-api';
 import { FrontendFeature } from '@backstage/frontend-plugin-api';
-import { IconComponent } from '@backstage/core-plugin-api';
 import { JSX as JSX_2 } from 'react';
 import { ReactNode } from 'react';
 import { RouteRef } from '@backstage/frontend-plugin-api';
@@ -14,9 +13,6 @@ import { SubRouteRef } from '@backstage/frontend-plugin-api';
 
 // @public (undocumented)
 export function createApp(options?: {
-  icons?: {
-    [key in string]: IconComponent;
-  };
   features?: (FrontendFeature | CreateAppFeatureLoader)[];
   configLoader?: () => Promise<{
     config: ConfigApi;
@@ -50,9 +46,6 @@ export type CreateAppRouteBinder = <
 
 // @public
 export function createSpecializedApp(options?: {
-  icons?: {
-    [key in string]: IconComponent;
-  };
   features?: FrontendFeature[];
   config?: ConfigApi;
   bindRoutes?(context: { bind: CreateAppRouteBinder }): void;
diff --git a/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.test.tsx b/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.test.tsx
index e2c7581e63..3d19fc413f 100644
--- a/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.test.tsx
+++ b/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.test.tsx
@@ -15,57 +15,22 @@
  */
 
 import React from 'react';
-import {
-  coreExtensionData,
-  createComponentExtension,
-  createComponentRef,
-  createExtension,
-  createExtensionOverrides,
-} from '@backstage/frontend-plugin-api';
-import { resolveAppNodeSpecs } from '../../../tree/resolveAppNodeSpecs';
-import { resolveAppTree } from '../../../tree/resolveAppTree';
-import { App } from '../../../extensions/App';
+import { createComponentRef } from '@backstage/frontend-plugin-api';
 import { DefaultComponentsApi } from './DefaultComponentsApi';
 import { render, screen } from '@testing-library/react';
-import { instantiateAppNodeTree } from '../../../tree/instantiateAppNodeTree';
 
 const testRefA = createComponentRef({ id: 'test.a' });
 const testRefB1 = createComponentRef({ id: 'test.b' });
 const testRefB2 = createComponentRef({ id: 'test.b' });
 
-const baseOverrides = createExtensionOverrides({
-  extensions: [
-    App,
-    createExtension({
-      namespace: 'app',
-      name: 'root',
-      attachTo: { id: 'app', input: 'root' },
-      output: [coreExtensionData.reactElement],
-      factory: () => [coreExtensionData.reactElement(<div>root</div>)],
-    }),
-  ],
-});
-
 describe('DefaultComponentsApi', () => {
   it('should provide components', () => {
-    const tree = resolveAppTree(
-      'app',
-      resolveAppNodeSpecs({
-        features: [
-          baseOverrides,
-          createExtensionOverrides({
-            extensions: [
-              createComponentExtension({
-                ref: testRefA,
-                loader: { sync: () => () => <div>test.a</div> },
-              }),
-            ],
-          }),
-        ],
-      }),
-    );
-    instantiateAppNodeTree(tree.root);
-    const api = DefaultComponentsApi.fromTree(tree);
+    const api = DefaultComponentsApi.fromComponents([
+      {
+        ref: testRefA,
+        impl: () => <div>test.a</div>,
+      },
+    ]);
 
     const ComponentA = api.getComponent(testRefA);
     render(<ComponentA />);
@@ -74,24 +39,12 @@ describe('DefaultComponentsApi', () => {
   });
 
   it('should key extension refs by ID', () => {
-    const tree = resolveAppTree(
-      'app',
-      resolveAppNodeSpecs({
-        features: [
-          baseOverrides,
-          createExtensionOverrides({
-            extensions: [
-              createComponentExtension({
-                ref: testRefB1,
-                loader: { sync: () => () => <div>test.b</div> },
-              }),
-            ],
-          }),
-        ],
-      }),
-    );
-    instantiateAppNodeTree(tree.root);
-    const api = DefaultComponentsApi.fromTree(tree);
+    const api = DefaultComponentsApi.fromComponents([
+      {
+        ref: testRefB1,
+        impl: () => <div>test.b</div>,
+      },
+    ]);
 
     const ComponentB1 = api.getComponent(testRefB1);
     const ComponentB2 = api.getComponent(testRefB2);
diff --git a/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.ts b/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.ts
index 572b6fc3c4..317233d797 100644
--- a/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.ts
+++ b/packages/frontend-app-api/src/apis/implementations/ComponentsApi/DefaultComponentsApi.ts
@@ -16,7 +16,6 @@
 
 import { ComponentType } from 'react';
 import {
-  AppTree,
   ComponentRef,
   ComponentsApi,
   createComponentExtension,
@@ -30,19 +29,12 @@ import {
 export class DefaultComponentsApi implements ComponentsApi {
   #components: Map<string, ComponentType<any>>;
 
-  static fromTree(tree: AppTree) {
-    const componentEntries = tree.root.edges.attachments
-      .get('components')
-      ?.reduce((map, e) => {
-        const data = e.instance?.getData(
-          createComponentExtension.componentDataRef,
-        );
-        if (data) {
-          map.set(data.ref.id, data.impl);
-        }
-        return map;
-      }, new Map<string, ComponentType>());
-    return new DefaultComponentsApi(componentEntries ?? new Map());
+  static fromComponents(
+    components: Array<typeof createComponentExtension.componentDataRef.T>,
+  ) {
+    return new DefaultComponentsApi(
+      new Map(components.map(entry => [entry.ref.id, entry.impl])),
+    );
   }
 
   constructor(components: Map<string, any>) {
diff --git a/packages/frontend-app-api/src/extensions/App.tsx b/packages/frontend-app-api/src/extensions/App.tsx
index ba6c5f65f1..e99b83eb5a 100644
--- a/packages/frontend-app-api/src/extensions/App.tsx
+++ b/packages/frontend-app-api/src/extensions/App.tsx
@@ -16,15 +16,11 @@
 
 import React from 'react';
 import {
+  ApiBlueprint,
   ExtensionBoundary,
   coreExtensionData,
-  createComponentExtension,
   createExtension,
   createExtensionInput,
-  IconBundleBlueprint,
-  ThemeBlueprint,
-  ApiBlueprint,
-  TranslationBlueprint,
 } from '@backstage/frontend-plugin-api';
 
 export const App = createExtension({
@@ -32,14 +28,6 @@ export const App = createExtension({
   attachTo: { id: 'root', input: 'default' }, // ignored
   inputs: {
     apis: createExtensionInput([ApiBlueprint.dataRefs.factory]),
-    themes: createExtensionInput([ThemeBlueprint.dataRefs.theme]),
-    components: createExtensionInput([
-      createComponentExtension.componentDataRef,
-    ]),
-    translations: createExtensionInput([
-      TranslationBlueprint.dataRefs.translation,
-    ]),
-    icons: createExtensionInput([IconBundleBlueprint.dataRefs.icons]),
     root: createExtensionInput([coreExtensionData.reactElement], {
       singleton: true,
     }),
diff --git a/packages/frontend-app-api/src/extensions/AppLanguageApi.ts b/packages/frontend-app-api/src/extensions/AppLanguageApi.ts
new file mode 100644
index 0000000000..ff12848d44
--- /dev/null
+++ b/packages/frontend-app-api/src/extensions/AppLanguageApi.ts
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import { AppLanguageSelector } from '../../../core-app-api/src/apis/implementations/AppLanguageApi';
+import { appLanguageApiRef } from '@backstage/core-plugin-api/alpha';
+import { ApiBlueprint, createApiFactory } from '@backstage/frontend-plugin-api';
+
+export const AppLanguageApi = ApiBlueprint.make({
+  name: 'app-language',
+  params: {
+    factory: createApiFactory(
+      appLanguageApiRef,
+      AppLanguageSelector.createWithStorage(),
+    ),
+  },
+});
diff --git a/packages/frontend-app-api/src/extensions/themes.tsx b/packages/frontend-app-api/src/extensions/AppThemeApi.tsx
similarity index 65%
rename from packages/frontend-app-api/src/extensions/themes.tsx
rename to packages/frontend-app-api/src/extensions/AppThemeApi.tsx
index a4fd0b253e..d0dcad34e8 100644
--- a/packages/frontend-app-api/src/extensions/themes.tsx
+++ b/packages/frontend-app-api/src/extensions/AppThemeApi.tsx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 The Backstage Authors
+ * Copyright 2024 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,34 @@ import {
 } from '@backstage/theme';
 import DarkIcon from '@material-ui/icons/Brightness2';
 import LightIcon from '@material-ui/icons/WbSunny';
-import { ThemeBlueprint } from '@backstage/frontend-plugin-api';
+import {
+  createExtensionInput,
+  ThemeBlueprint,
+  ApiBlueprint,
+  createApiFactory,
+  appThemeApiRef,
+} from '@backstage/frontend-plugin-api';
+import { AppThemeSelector } from '@backstage/core-app-api';
+
+/**
+ * Contains the themes installed into the app.
+ */
+export const AppThemeApi = ApiBlueprint.makeWithOverrides({
+  name: 'app-theme',
+  inputs: {
+    themes: createExtensionInput([ThemeBlueprint.dataRefs.theme]),
+  },
+  factory: (originalFactory, { inputs }) => {
+    return originalFactory({
+      factory: createApiFactory(
+        appThemeApiRef,
+        AppThemeSelector.createWithStorage(
+          inputs.themes.map(i => i.get(ThemeBlueprint.dataRefs.theme)),
+        ),
+      ),
+    });
+  },
+});
 
 export const LightTheme = ThemeBlueprint.make({
   name: 'light',
diff --git a/packages/frontend-app-api/src/extensions/ComponentsApi.tsx b/packages/frontend-app-api/src/extensions/ComponentsApi.tsx
new file mode 100644
index 0000000000..5803aacf95
--- /dev/null
+++ b/packages/frontend-app-api/src/extensions/ComponentsApi.tsx
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  createComponentExtension,
+  createExtensionInput,
+  ApiBlueprint,
+  createApiFactory,
+  componentsApiRef,
+} from '@backstage/frontend-plugin-api';
+import { DefaultComponentsApi } from '../apis/implementations/ComponentsApi';
+
+/**
+ * Contains the shareable components installed into the app.
+ */
+export const ComponentsApi = ApiBlueprint.makeWithOverrides({
+  name: 'components',
+  inputs: {
+    components: createExtensionInput([
+      createComponentExtension.componentDataRef,
+    ]),
+  },
+  factory: (originalFactory, { inputs }) => {
+    return originalFactory({
+      factory: createApiFactory(
+        componentsApiRef,
+        DefaultComponentsApi.fromComponents(
+          inputs.components.map(i =>
+            i.get(createComponentExtension.componentDataRef),
+          ),
+        ),
+      ),
+    });
+  },
+});
diff --git a/packages/frontend-app-api/src/extensions/FeatureFlagsApi.ts b/packages/frontend-app-api/src/extensions/FeatureFlagsApi.ts
new file mode 100644
index 0000000000..8016521539
--- /dev/null
+++ b/packages/frontend-app-api/src/extensions/FeatureFlagsApi.ts
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  ApiBlueprint,
+  createApiFactory,
+  featureFlagsApiRef,
+} from '@backstage/frontend-plugin-api';
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import { LocalStorageFeatureFlags } from '../../../core-app-api/src/apis/implementations/FeatureFlagsApi/LocalStorageFeatureFlags';
+
+/**
+ * Contains the shareable icons installed into the app.
+ */
+export const FeatureFlagsApi = ApiBlueprint.make({
+  name: 'feature-flags',
+  params: {
+    // TODO: properly discovery feature flags, maybe rework the whole thing
+    factory: createApiFactory({
+      api: featureFlagsApiRef,
+      deps: {},
+      factory: () => new LocalStorageFeatureFlags(),
+    }),
+  },
+});
diff --git a/packages/frontend-app-api/src/extensions/IconsApi.ts b/packages/frontend-app-api/src/extensions/IconsApi.ts
new file mode 100644
index 0000000000..d770000197
--- /dev/null
+++ b/packages/frontend-app-api/src/extensions/IconsApi.ts
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  createExtensionInput,
+  IconBundleBlueprint,
+  ApiBlueprint,
+  createApiFactory,
+  iconsApiRef,
+} from '@backstage/frontend-plugin-api';
+import { DefaultIconsApi } from '../apis/implementations/IconsApi';
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import { icons as defaultIcons } from '../../../app-defaults/src/defaults';
+
+/**
+ * Contains the shareable icons installed into the app.
+ */
+export const IconsApi = ApiBlueprint.makeWithOverrides({
+  name: 'icons',
+  inputs: {
+    icons: createExtensionInput([IconBundleBlueprint.dataRefs.icons]),
+  },
+  factory: (originalFactory, { inputs }) => {
+    return originalFactory({
+      factory: createApiFactory(
+        iconsApiRef,
+        new DefaultIconsApi(
+          inputs.icons
+            .map(i => i.get(IconBundleBlueprint.dataRefs.icons))
+            .reduce((acc, bundle) => ({ ...acc, ...bundle }), defaultIcons),
+        ),
+      ),
+    });
+  },
+});
diff --git a/packages/frontend-app-api/src/extensions/TranslationsApi.tsx b/packages/frontend-app-api/src/extensions/TranslationsApi.tsx
new file mode 100644
index 0000000000..9c13c3b063
--- /dev/null
+++ b/packages/frontend-app-api/src/extensions/TranslationsApi.tsx
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import {
+  ApiBlueprint,
+  TranslationBlueprint,
+  createApiFactory,
+  createExtensionInput,
+} from '@backstage/frontend-plugin-api';
+import {
+  appLanguageApiRef,
+  translationApiRef,
+} from '@backstage/core-plugin-api/alpha';
+
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import { I18nextTranslationApi } from '../../../core-app-api/src/apis/implementations/TranslationApi/I18nextTranslationApi';
+
+/**
+ * Contains translations that are installed in the app.
+ */
+export const TranslationsApi = ApiBlueprint.makeWithOverrides({
+  name: 'translations',
+  inputs: {
+    translations: createExtensionInput([
+      TranslationBlueprint.dataRefs.translation,
+    ]),
+  },
+  factory: (originalFactory, { inputs }) => {
+    return originalFactory({
+      factory: createApiFactory({
+        api: translationApiRef,
+        deps: { languageApi: appLanguageApiRef },
+        factory: ({ languageApi }) =>
+          I18nextTranslationApi.create({
+            languageApi,
+            resources: inputs.translations.map(i =>
+              i.get(TranslationBlueprint.dataRefs.translation),
+            ),
+          }),
+      }),
+    });
+  },
+});
diff --git a/packages/frontend-app-api/src/wiring/createApp.test.tsx b/packages/frontend-app-api/src/wiring/createApp.test.tsx
index c79d8eed76..6fc4720da2 100644
--- a/packages/frontend-app-api/src/wiring/createApp.test.tsx
+++ b/packages/frontend-app-api/src/wiring/createApp.test.tsx
@@ -278,16 +278,24 @@ describe('createApp', () => {
             ]
           </app/root>
         ]
-        components [
-          <component:core.components.progress out=[core.component.component] />
-          <component:core.components.errorBoundaryFallback out=[core.component.component] />
-          <component:core.components.notFoundErrorPage out=[core.component.component] />
-        ]
-        themes [
-          <theme:app/light out=[core.theme.theme] />
-          <theme:app/dark out=[core.theme.theme] />
-        ]
         apis [
+          <api:app-theme out=[core.api.factory]>
+            themes [
+              <theme:app/light out=[core.theme.theme] />
+              <theme:app/dark out=[core.theme.theme] />
+            ]
+          </api:app-theme>
+          <api:app-language out=[core.api.factory] />
+          <api:icons out=[core.api.factory] />
+          <api:translations out=[core.api.factory] />
+          <api:components out=[core.api.factory]>
+            components [
+              <component:core.components.progress out=[core.component.component] />
+              <component:core.components.errorBoundaryFallback out=[core.component.component] />
+              <component:core.components.notFoundErrorPage out=[core.component.component] />
+            ]
+          </api:components>
+          <api:feature-flags out=[core.api.factory] />
           <api:core.discovery out=[core.api.factory] />
           <api:core.alert out=[core.api.factory] />
           <api:core.analytics out=[core.api.factory] />
diff --git a/packages/frontend-app-api/src/wiring/createApp.tsx b/packages/frontend-app-api/src/wiring/createApp.tsx
index ca42dce3e4..37594f74d4 100644
--- a/packages/frontend-app-api/src/wiring/createApp.tsx
+++ b/packages/frontend-app-api/src/wiring/createApp.tsx
@@ -20,15 +20,10 @@ import {
   ApiBlueprint,
   AppTree,
   appTreeApiRef,
-  componentsApiRef,
   coreExtensionData,
   FrontendFeature,
-  IconBundleBlueprint,
-  iconsApiRef,
   RouteResolutionApi,
   routeResolutionApiRef,
-  ThemeBlueprint,
-  TranslationBlueprint,
 } from '@backstage/frontend-plugin-api';
 import { App } from '../extensions/App';
 import { AppRoutes } from '../extensions/AppRoutes';
@@ -37,13 +32,10 @@ import { AppNav } from '../extensions/AppNav';
 import {
   AnyApiFactory,
   ApiHolder,
-  appThemeApiRef,
   ConfigApi,
   configApiRef,
-  IconComponent,
   featureFlagsApiRef,
   identityApiRef,
-  AppTheme,
   errorApiRef,
   discoveryApiRef,
   fetchApiRef,
@@ -53,7 +45,6 @@ import {
   ApiFactoryRegistry,
   ApiProvider,
   ApiResolver,
-  AppThemeSelector,
 } from '@backstage/core-app-api';
 
 // TODO: Get rid of all of these
@@ -64,29 +55,20 @@ import { AppThemeProvider } from '../../../core-app-api/src/app/AppThemeProvider
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { AppIdentityProxy } from '../../../core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { LocalStorageFeatureFlags } from '../../../core-app-api/src/apis/implementations/FeatureFlagsApi/LocalStorageFeatureFlags';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { defaultConfigLoaderSync } from '../../../core-app-api/src/app/defaultConfigLoader';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { overrideBaseUrlConfigs } from '../../../core-app-api/src/app/overrideBaseUrlConfigs';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { AppLanguageSelector } from '../../../core-app-api/src/apis/implementations/AppLanguageApi/AppLanguageSelector';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { I18nextTranslationApi } from '../../../core-app-api/src/apis/implementations/TranslationApi/I18nextTranslationApi';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { resolveExtensionDefinition } from '../../../frontend-plugin-api/src/wiring/resolveExtensionDefinition';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { apis as defaultApis } from '../../../app-defaults/src/defaults';
-import { DarkTheme, LightTheme } from '../extensions/themes';
+
 import {
   oauthRequestDialogAppRootElement,
   alertDisplayAppRootElement,
 } from '../extensions/elements';
 import { extractRouteInfoFromAppNode } from '../routing/extractRouteInfoFromAppNode';
-import {
-  appLanguageApiRef,
-  translationApiRef,
-} from '@backstage/core-plugin-api/alpha';
+
 import { CreateAppRouteBinder } from '../routing';
 import { RouteResolver } from '../routing/RouteResolver';
 import { resolveRouteBindings } from '../routing/resolveRouteBindings';
@@ -103,12 +85,14 @@ import { AppRoot } from '../extensions/AppRoot';
 import { toInternalBackstagePlugin } from '../../../frontend-plugin-api/src/wiring/createFrontendPlugin';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { toInternalExtensionOverrides } from '../../../frontend-plugin-api/src/wiring/createExtensionOverrides';
-import { DefaultComponentsApi } from '../apis/implementations/ComponentsApi';
-import { DefaultIconsApi } from '../apis/implementations/IconsApi';
 import { stringifyError } from '@backstage/errors';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { icons as defaultIcons } from '../../../app-defaults/src/defaults';
 import { getBasePath } from '../routing/getBasePath';
+import { AppThemeApi, DarkTheme, LightTheme } from '../extensions/AppThemeApi';
+import { IconsApi } from '../extensions/IconsApi';
+import { TranslationsApi } from '../extensions/TranslationsApi';
+import { ComponentsApi } from '../extensions/ComponentsApi';
+import { AppLanguageApi } from '../extensions/AppLanguageApi';
+import { FeatureFlagsApi } from '../extensions/FeatureFlagsApi';
 
 const DefaultApis = defaultApis.map(factory =>
   ApiBlueprint.make({ namespace: factory.api.id, params: { factory } }),
@@ -127,6 +111,12 @@ export const builtinExtensions = [
   DarkTheme,
   oauthRequestDialogAppRootElement,
   alertDisplayAppRootElement,
+  AppThemeApi,
+  AppLanguageApi,
+  IconsApi,
+  TranslationsApi,
+  ComponentsApi,
+  FeatureFlagsApi,
   ...DefaultApis,
 ].map(def => resolveExtensionDefinition(def));
 
@@ -174,8 +164,6 @@ export interface CreateAppFeatureLoader {
 
 /** @public */
 export function createApp(options?: {
-  /** @deprecated - Please use {@link @backstage/frontend-plugin-api#IconBundleBlueprint} to make new icon bundles which can be installed in the app seperately */
-  icons?: { [key in string]: IconComponent };
   features?: (FrontendFeature | CreateAppFeatureLoader)[];
   configLoader?: () => Promise<{ config: ConfigApi }>;
   bindRoutes?(context: { bind: CreateAppRouteBinder }): void;
@@ -222,7 +210,6 @@ export function createApp(options?: {
     }
 
     const app = createSpecializedApp({
-      icons: options?.icons,
       config,
       features: [...discoveredFeatures, ...providedFeatures],
       bindRoutes: options?.bindRoutes,
@@ -250,8 +237,6 @@ export function createApp(options?: {
  * @public
  */
 export function createSpecializedApp(options?: {
-  /** @deprecated - Please use {@link @backstage/frontend-plugin-api#IconBundleBlueprint} to make new icon bundles which can be installed in the app seperately */
-  icons?: { [key in string]: IconComponent };
   features?: FrontendFeature[];
   config?: ConfigApi;
   bindRoutes?(context: { bind: CreateAppRouteBinder }): void;
@@ -288,7 +273,6 @@ export function createSpecializedApp(options?: {
       routeBindings,
       getBasePath(config),
     ),
-    options?.icons,
   );
 
   if (isProtectedApp()) {
@@ -352,7 +336,6 @@ function createApiHolder(
   configApi: ConfigApi,
   appIdentityProxy: AppIdentityProxy,
   routeResolutionApi: RouteResolutionApi,
-  icons?: { [key in string]: IconComponent },
 ): ApiHolder {
   const factoryRegistry = new ApiFactoryRegistry();
 
@@ -362,36 +345,10 @@ function createApiHolder(
       ?.map(e => e.instance?.getData(ApiBlueprint.dataRefs.factory))
       .filter((x): x is AnyApiFactory => !!x) ?? [];
 
-  const themeExtensions =
-    tree.root.edges.attachments
-      .get('themes')
-      ?.map(e => e.instance?.getData(ThemeBlueprint.dataRefs.theme))
-      .filter((x): x is AppTheme => !!x) ?? [];
-
-  const translationResources =
-    tree.root.edges.attachments
-      .get('translations')
-      ?.map(e => e.instance?.getData(TranslationBlueprint.dataRefs.translation))
-      .filter(
-        (x): x is typeof TranslationBlueprint.dataRefs.translation.T => !!x,
-      ) ?? [];
-
-  const extensionIcons = tree.root.edges.attachments
-    .get('icons')
-    ?.map(e => e.instance?.getData(IconBundleBlueprint.dataRefs.icons))
-    .reduce((acc, bundle) => ({ ...acc, ...bundle }), {});
-
   for (const factory of pluginApis) {
     factoryRegistry.register('default', factory);
   }
 
-  // TODO: properly discovery feature flags, maybe rework the whole thing
-  factoryRegistry.register('default', {
-    api: featureFlagsApiRef,
-    deps: {},
-    factory: () => new LocalStorageFeatureFlags(),
-  });
-
   factoryRegistry.register('static', {
     api: identityApiRef,
     deps: {},
@@ -412,54 +369,12 @@ function createApiHolder(
     factory: () => routeResolutionApi,
   });
 
-  factoryRegistry.register('static', {
-    api: componentsApiRef,
-    deps: {},
-    factory: () => DefaultComponentsApi.fromTree(tree),
-  });
-
-  factoryRegistry.register('static', {
-    api: iconsApiRef,
-    deps: {},
-    factory: () =>
-      new DefaultIconsApi({ ...defaultIcons, ...extensionIcons, ...icons }),
-  });
-
-  factoryRegistry.register('static', {
-    api: appThemeApiRef,
-    deps: {},
-    // TODO: add extension for registering themes
-    factory: () => AppThemeSelector.createWithStorage(themeExtensions),
-  });
-
-  factoryRegistry.register('static', {
-    api: appLanguageApiRef,
-    deps: {},
-    factory: () => AppLanguageSelector.createWithStorage(),
-  });
-
   factoryRegistry.register('static', {
     api: configApiRef,
     deps: {},
     factory: () => configApi,
   });
 
-  factoryRegistry.register('static', {
-    api: appLanguageApiRef,
-    deps: {},
-    factory: () => AppLanguageSelector.createWithStorage(),
-  });
-
-  factoryRegistry.register('static', {
-    api: translationApiRef,
-    deps: { languageApi: appLanguageApiRef },
-    factory: ({ languageApi }) =>
-      I18nextTranslationApi.create({
-        languageApi,
-        resources: translationResources,
-      }),
-  });
-
   ApiResolver.validateFactories(factoryRegistry, factoryRegistry.getAllApis());
 
   return new ApiResolver(factoryRegistry);
diff --git a/packages/frontend-plugin-api/src/blueprints/IconBundleBlueprint.ts b/packages/frontend-plugin-api/src/blueprints/IconBundleBlueprint.ts
index 52d6e2482d..de2df761ff 100644
--- a/packages/frontend-plugin-api/src/blueprints/IconBundleBlueprint.ts
+++ b/packages/frontend-plugin-api/src/blueprints/IconBundleBlueprint.ts
@@ -25,7 +25,7 @@ const iconsDataRef = createExtensionDataRef<{
 export const IconBundleBlueprint = createExtensionBlueprint({
   kind: 'icon-bundle',
   namespace: 'app',
-  attachTo: { id: 'app', input: 'icons' },
+  attachTo: { id: 'api:icons', input: 'icons' },
   output: [iconsDataRef],
   config: {
     schema: {
diff --git a/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.test.ts b/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.test.ts
index e6daf510eb..75d342fdcb 100644
--- a/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.test.ts
+++ b/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.test.ts
@@ -32,7 +32,7 @@ describe('ThemeBlueprint', () => {
       {
         "$$type": "@backstage/ExtensionDefinition",
         "attachTo": {
-          "id": "app",
+          "id": "api:app-theme",
           "input": "themes",
         },
         "configSchema": undefined,
diff --git a/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.ts b/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.ts
index a4f550595f..c06078b122 100644
--- a/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.ts
+++ b/packages/frontend-plugin-api/src/blueprints/ThemeBlueprint.ts
@@ -29,7 +29,7 @@ const themeDataRef = createExtensionDataRef<AppTheme>().with({
 export const ThemeBlueprint = createExtensionBlueprint({
   kind: 'theme',
   namespace: 'app',
-  attachTo: { id: 'app', input: 'themes' },
+  attachTo: { id: 'api:app-theme', input: 'themes' },
   output: [themeDataRef],
   dataRefs: {
     theme: themeDataRef,
diff --git a/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.test.ts b/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.test.ts
index 3c7b271322..65ef4f7ee0 100644
--- a/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.test.ts
+++ b/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.test.ts
@@ -47,7 +47,7 @@ describe('TranslationBlueprint', () => {
       {
         "$$type": "@backstage/ExtensionDefinition",
         "attachTo": {
-          "id": "app",
+          "id": "api:translations",
           "input": "translations",
         },
         "configSchema": undefined,
diff --git a/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.ts b/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.ts
index 7b01d0b28f..ea7aa64713 100644
--- a/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.ts
+++ b/packages/frontend-plugin-api/src/blueprints/TranslationBlueprint.ts
@@ -28,7 +28,7 @@ const translationDataRef = createExtensionDataRef<
  */
 export const TranslationBlueprint = createExtensionBlueprint({
   kind: 'translation',
-  attachTo: { id: 'app', input: 'translations' },
+  attachTo: { id: 'api:translations', input: 'translations' },
   output: [translationDataRef],
   dataRefs: {
     translation: translationDataRef,
diff --git a/packages/frontend-plugin-api/src/extensions/createComponentExtension.tsx b/packages/frontend-plugin-api/src/extensions/createComponentExtension.tsx
index 9561636d22..35d003e99b 100644
--- a/packages/frontend-plugin-api/src/extensions/createComponentExtension.tsx
+++ b/packages/frontend-plugin-api/src/extensions/createComponentExtension.tsx
@@ -35,7 +35,7 @@ export function createComponentExtension<TProps extends {}>(options: {
     kind: 'component',
     namespace: options.ref.id,
     name: options.name,
-    attachTo: { id: 'app', input: 'components' },
+    attachTo: { id: 'api:components', input: 'components' },
     disabled: options.disabled,
     output: [createComponentExtension.componentDataRef],
     factory() {