diff --git a/.changeset/silent-horses-raise.md b/.changeset/silent-horses-raise.md
index de2671c3da..a03d662b03 100644
--- a/.changeset/silent-horses-raise.md
+++ b/.changeset/silent-horses-raise.md
@@ -4,4 +4,4 @@
 '@backstage/frontend-app-api': patch
 ---
 
-Added `elements` and `wrappers` inputs to `app/root`, that let you add things to the root of the React tree above the layout. You can use the `createAppRootElementExtension` and `createAppRootWrapperExtension` extension creator, respectively, to conveniently create such extensions.
+Added `elements`, `wrappers`, and `router` inputs to `app/root`, that let you add things to the root of the React tree above the layout. You can use the `createAppRootElementExtension`, `createAppRootWrapperExtension`, and `createRouterExtension` extension creator, respectively, to conveniently create such extensions. These are all optional, and if you do not supply a router a default one will be used (`BrowserRouter` in regular runs, `MemoryRouter` in tests/CI).
diff --git a/packages/frontend-app-api/src/extensions/AppRoot.tsx b/packages/frontend-app-api/src/extensions/AppRoot.tsx
index 883074ca00..2b709f4e42 100644
--- a/packages/frontend-app-api/src/extensions/AppRoot.tsx
+++ b/packages/frontend-app-api/src/extensions/AppRoot.tsx
@@ -17,6 +17,7 @@
 import React, {
   ComponentType,
   Fragment,
+  PropsWithChildren,
   ReactNode,
   useContext,
   useState,
@@ -26,6 +27,7 @@ import {
   createAppRootWrapperExtension,
   createExtension,
   createExtensionInput,
+  createRouterExtension,
   createSignInPageExtension,
 } from '@backstage/frontend-plugin-api';
 import {
@@ -46,6 +48,10 @@ export const AppRoot = createExtension({
   name: 'root',
   attachTo: { id: 'app', input: 'root' },
   inputs: {
+    router: createExtensionInput(
+      { component: createRouterExtension.componentDataRef },
+      { singleton: true, optional: true },
+    ),
     signInPage: createExtensionInput(
       { component: createSignInPageExtension.componentDataRef },
       { singleton: true, optional: true },
@@ -80,7 +86,10 @@ export const AppRoot = createExtension({
 
     return {
       element: (
-        <AppRouter SignInPageComponent={inputs.signInPage?.output.component}>
+        <AppRouter
+          SignInPageComponent={inputs.signInPage?.output.component}
+          RouterComponent={inputs.router?.output.component}
+        >
           {content}
         </AppRouter>
       ),
@@ -133,12 +142,18 @@ function SignInPageWrapper({
 export interface AppRouterProps {
   children?: ReactNode;
   SignInPageComponent?: ComponentType<SignInPageProps>;
+  RouterComponent?: ComponentType<PropsWithChildren<{}>>;
+}
+
+function DefaultRouter(props: PropsWithChildren<{}>) {
+  const configApi = useApi(configApiRef);
+  const basePath = getBasePath(configApi);
+  return <BrowserRouter basename={basePath}>{props.children}</BrowserRouter>;
 }
 
 /**
  * App router and sign-in page wrapper.
  *
- * @public
  * @remarks
  *
  * The AppRouter provides the routing context and renders the sign-in page.
@@ -147,7 +162,11 @@ export interface AppRouterProps {
  * the app, while providing routing and route tracking for the app.
  */
 export function AppRouter(props: AppRouterProps) {
-  const { children, SignInPageComponent } = props;
+  const {
+    children,
+    SignInPageComponent,
+    RouterComponent = DefaultRouter,
+  } = props;
 
   const configApi = useApi(configApiRef);
   const basePath = getBasePath(configApi);
@@ -183,15 +202,15 @@ export function AppRouter(props: AppRouterProps) {
     );
 
     return (
-      <BrowserRouter basename={basePath}>
+      <RouterComponent>
         <RouteTracker routeObjects={routeObjects} />
         {children}
-      </BrowserRouter>
+      </RouterComponent>
     );
   }
 
   return (
-    <BrowserRouter basename={basePath}>
+    <RouterComponent>
       <RouteTracker routeObjects={routeObjects} />
       <SignInPageWrapper
         component={SignInPageComponent}
@@ -199,6 +218,6 @@ export function AppRouter(props: AppRouterProps) {
       >
         {children}
       </SignInPageWrapper>
-    </BrowserRouter>
+    </RouterComponent>
   );
 }
diff --git a/packages/frontend-plugin-api/api-report.md b/packages/frontend-plugin-api/api-report.md
index 6113c946ee..1d42d8bab8 100644
--- a/packages/frontend-plugin-api/api-report.md
+++ b/packages/frontend-plugin-api/api-report.md
@@ -687,6 +687,39 @@ export function createRouteRef<
       }
 >;
 
+// @public
+export function createRouterExtension<
+  TConfig extends {},
+  TInputs extends AnyExtensionInputMap,
+>(options: {
+  namespace?: string;
+  name?: string;
+  attachTo?: {
+    id: string;
+    input: string;
+  };
+  configSchema?: PortableSchema<TConfig>;
+  disabled?: boolean;
+  inputs?: TInputs;
+  Component: ComponentType<
+    PropsWithChildren<{
+      inputs: Expand<ResolvedExtensionInputs<TInputs>>;
+      config: TConfig;
+    }>
+  >;
+}): ExtensionDefinition<TConfig>;
+
+// @public (undocumented)
+export namespace createRouterExtension {
+  const // (undocumented)
+    componentDataRef: ConfigurableExtensionDataRef<
+      React_2.ComponentType<{
+        children?: React_2.ReactNode;
+      }>,
+      {}
+    >;
+}
+
 // @public (undocumented)
 export function createSchemaFromZod<TOutput, TInput>(
   schemaCreator: (zImpl: typeof z) => ZodSchema<TOutput, ZodTypeDef, TInput>,
diff --git a/packages/frontend-plugin-api/package.json b/packages/frontend-plugin-api/package.json
index 4722cd1bff..007d76764b 100644
--- a/packages/frontend-plugin-api/package.json
+++ b/packages/frontend-plugin-api/package.json
@@ -22,6 +22,21 @@
     "prepack": "backstage-cli package prepack",
     "postpack": "backstage-cli package postpack"
   },
+  "dependencies": {
+    "@backstage/core-components": "workspace:^",
+    "@backstage/core-plugin-api": "workspace:^",
+    "@backstage/types": "workspace:^",
+    "@backstage/version-bridge": "workspace:^",
+    "@material-ui/core": "^4.12.4",
+    "@types/react": "^16.13.1 || ^17.0.0",
+    "lodash": "^4.17.21",
+    "zod": "^3.22.4",
+    "zod-to-json-schema": "^3.21.4"
+  },
+  "peerDependencies": {
+    "react": "^16.13.1 || ^17.0.0 || ^18.0.0",
+    "react-router-dom": "6.0.0-beta.0 || ^6.3.0"
+  },
   "devDependencies": {
     "@backstage/cli": "workspace:^",
     "@backstage/frontend-app-api": "workspace:^",
@@ -33,20 +48,5 @@
   },
   "files": [
     "dist"
-  ],
-  "peerDependencies": {
-    "react": "^16.13.1 || ^17.0.0 || ^18.0.0",
-    "react-router-dom": "6.0.0-beta.0 || ^6.3.0"
-  },
-  "dependencies": {
-    "@backstage/core-components": "workspace:^",
-    "@backstage/core-plugin-api": "workspace:^",
-    "@backstage/types": "workspace:^",
-    "@backstage/version-bridge": "workspace:^",
-    "@material-ui/core": "^4.12.4",
-    "@types/react": "^16.13.1 || ^17.0.0",
-    "lodash": "^4.17.21",
-    "zod": "^3.22.4",
-    "zod-to-json-schema": "^3.21.4"
-  }
+  ]
 }
diff --git a/packages/frontend-plugin-api/src/extensions/createRouterExtension.test.tsx b/packages/frontend-plugin-api/src/extensions/createRouterExtension.test.tsx
new file mode 100644
index 0000000000..7109e1a8aa
--- /dev/null
+++ b/packages/frontend-plugin-api/src/extensions/createRouterExtension.test.tsx
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2023 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 { createSpecializedApp } from '@backstage/frontend-app-api';
+import { render, screen } from '@testing-library/react';
+import React from 'react';
+import { MockConfigApi } from '@backstage/test-utils';
+import { MemoryRouter } from 'react-router-dom';
+import { createSchemaFromZod } from '../schema/createSchemaFromZod';
+import { coreExtensionData } from '../wiring/coreExtensionData';
+import { createExtension } from '../wiring/createExtension';
+import { createExtensionInput } from '../wiring/createExtensionInput';
+import { createExtensionOverrides } from '../wiring/createExtensionOverrides';
+import { createPageExtension } from './createPageExtension';
+import { createRouterExtension } from './createRouterExtension';
+
+describe('createRouterExtension', () => {
+  it('works with simple options and no props', async () => {
+    const extension = createRouterExtension({
+      namespace: 'test',
+      Component: ({ children }) => (
+        <MemoryRouter>
+          <div data-testid="test-router">{children}</div>
+        </MemoryRouter>
+      ),
+    });
+
+    expect(extension).toEqual({
+      $$type: '@backstage/ExtensionDefinition',
+      version: 'v1',
+      kind: 'app-router-component',
+      namespace: 'test',
+      attachTo: { id: 'app/root', input: 'router' },
+      disabled: false,
+      inputs: {},
+      output: {
+        component: expect.anything(),
+      },
+      factory: expect.any(Function),
+      toString: expect.any(Function),
+    });
+
+    const app = createSpecializedApp({
+      features: [
+        createExtensionOverrides({
+          extensions: [
+            extension,
+            createPageExtension({
+              namespace: 'test',
+              defaultPath: '/',
+              loader: async () => <div data-testid="test-contents" />,
+            }),
+          ],
+        }),
+      ],
+    });
+
+    render(app.createRoot());
+
+    await expect(
+      screen.findByTestId('test-contents'),
+    ).resolves.toBeInTheDocument();
+    await expect(
+      screen.findByTestId('test-router'),
+    ).resolves.toBeInTheDocument();
+  });
+
+  it('works with complex options and props', async () => {
+    const schema = createSchemaFromZod(z => z.object({ name: z.string() }));
+
+    const extension = createRouterExtension({
+      namespace: 'test',
+      name: 'test',
+      configSchema: schema,
+      inputs: {
+        children: createExtensionInput({
+          element: coreExtensionData.reactElement,
+        }),
+      },
+      Component: ({ inputs, config, children }) => (
+        <MemoryRouter>
+          <div
+            data-testid={`test-router-${config.name}-${inputs.children.length}`}
+          >
+            {children}
+          </div>
+        </MemoryRouter>
+      ),
+    });
+
+    expect(extension).toEqual({
+      $$type: '@backstage/ExtensionDefinition',
+      version: 'v1',
+      kind: 'app-router-component',
+      namespace: 'test',
+      name: 'test',
+      attachTo: { id: 'app/root', input: 'router' },
+      configSchema: schema,
+      disabled: false,
+      inputs: {
+        children: createExtensionInput({
+          element: coreExtensionData.reactElement,
+        }),
+      },
+      output: {
+        component: expect.anything(),
+      },
+      factory: expect.any(Function),
+      toString: expect.any(Function),
+    });
+
+    const app = createSpecializedApp({
+      features: [
+        createExtensionOverrides({
+          extensions: [
+            extension,
+            createExtension({
+              namespace: 'test',
+              attachTo: {
+                id: 'app-router-component:test/test',
+                input: 'children',
+              },
+              output: { element: coreExtensionData.reactElement }, // doesn't matter
+              factory: () => ({ element: <div /> }),
+            }),
+            createPageExtension({
+              namespace: 'test',
+              defaultPath: '/',
+              loader: async () => <div data-testid="test-contents" />,
+            }),
+          ],
+        }),
+      ],
+      config: new MockConfigApi({
+        app: {
+          extensions: [
+            {
+              'app-router-component:test/test': { config: { name: 'Robin' } },
+            },
+          ],
+        },
+      }),
+    });
+
+    render(app.createRoot());
+
+    await expect(
+      screen.findByTestId('test-contents'),
+    ).resolves.toBeInTheDocument();
+    await expect(
+      screen.findByTestId('test-router-Robin-1'),
+    ).resolves.toBeInTheDocument();
+  });
+});
diff --git a/packages/frontend-plugin-api/src/extensions/createRouterExtension.tsx b/packages/frontend-plugin-api/src/extensions/createRouterExtension.tsx
new file mode 100644
index 0000000000..32d61f7e60
--- /dev/null
+++ b/packages/frontend-plugin-api/src/extensions/createRouterExtension.tsx
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2023 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 React, { ComponentType, PropsWithChildren } from 'react';
+import { PortableSchema } from '../schema/types';
+import {
+  AnyExtensionInputMap,
+  ExtensionDefinition,
+  ResolvedExtensionInputs,
+  createExtension,
+} from '../wiring/createExtension';
+import { createExtensionDataRef } from '../wiring/createExtensionDataRef';
+import { Expand } from '../types';
+
+/**
+ * Creates an extension that replaces the router implementation at the app root.
+ * This is useful to be able to for example replace the BrowserRouter with a
+ * MemoryRouter in tests, or to add additional props to a BrowserRouter.
+ *
+ * @public
+ */
+export function createRouterExtension<
+  TConfig extends {},
+  TInputs extends AnyExtensionInputMap,
+>(options: {
+  namespace?: string;
+  name?: string;
+  attachTo?: { id: string; input: string };
+  configSchema?: PortableSchema<TConfig>;
+  disabled?: boolean;
+  inputs?: TInputs;
+  Component: ComponentType<
+    PropsWithChildren<{
+      inputs: Expand<ResolvedExtensionInputs<TInputs>>;
+      config: TConfig;
+    }>
+  >;
+}): ExtensionDefinition<TConfig> {
+  return createExtension({
+    kind: 'app-router-component',
+    namespace: options.namespace,
+    name: options.name,
+    attachTo: options.attachTo ?? { id: 'app/root', input: 'router' },
+    configSchema: options.configSchema,
+    disabled: options.disabled,
+    inputs: options.inputs,
+    output: {
+      component: createRouterExtension.componentDataRef,
+    },
+    factory({ inputs, config }) {
+      const Component = (props: PropsWithChildren<{}>) => {
+        return (
+          <options.Component inputs={inputs} config={config}>
+            {props.children}
+          </options.Component>
+        );
+      };
+      return {
+        component: Component,
+      };
+    },
+  });
+}
+
+/** @public */
+export namespace createRouterExtension {
+  export const componentDataRef =
+    createExtensionDataRef<ComponentType<PropsWithChildren<{}>>>(
+      'app.router.wrapper',
+    );
+}
diff --git a/packages/frontend-plugin-api/src/extensions/index.ts b/packages/frontend-plugin-api/src/extensions/index.ts
index 40e9f6f56d..562cb728cb 100644
--- a/packages/frontend-plugin-api/src/extensions/index.ts
+++ b/packages/frontend-plugin-api/src/extensions/index.ts
@@ -17,6 +17,7 @@
 export { createApiExtension } from './createApiExtension';
 export { createAppRootElementExtension } from './createAppRootElementExtension';
 export { createAppRootWrapperExtension } from './createAppRootWrapperExtension';
+export { createRouterExtension } from './createRouterExtension';
 export { createPageExtension } from './createPageExtension';
 export { createNavItemExtension } from './createNavItemExtension';
 export { createNavLogoExtension } from './createNavLogoExtension';
diff --git a/packages/frontend-test-utils/src/app/createExtensionTester.test.tsx b/packages/frontend-test-utils/src/app/createExtensionTester.test.tsx
index 40baaa3ac9..d53344f7fd 100644
--- a/packages/frontend-test-utils/src/app/createExtensionTester.test.tsx
+++ b/packages/frontend-test-utils/src/app/createExtensionTester.test.tsx
@@ -219,10 +219,14 @@ describe('createExtensionTester', () => {
     fireEvent.click(await screen.findByRole('button', { name: 'See details' }));
 
     await waitFor(() =>
-      expect(analyticsApiMock.getEvents()[0]).toMatchObject({
-        action: 'click',
-        subject: 'See details',
-      }),
+      expect(analyticsApiMock.getEvents()).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            action: 'click',
+            subject: 'See details',
+          }),
+        ]),
+      ),
     );
   });
 });
diff --git a/packages/frontend-test-utils/src/app/createExtensionTester.tsx b/packages/frontend-test-utils/src/app/createExtensionTester.tsx
index 2984af9dbf..a98879fbba 100644
--- a/packages/frontend-test-utils/src/app/createExtensionTester.tsx
+++ b/packages/frontend-test-utils/src/app/createExtensionTester.tsx
@@ -14,29 +14,20 @@
  * limitations under the License.
  */
 
-import React, {
-  ComponentType,
-  Fragment,
-  ReactNode,
-  useContext,
-  useState,
-} from 'react';
+import React from 'react';
 import { MemoryRouter, Link } from 'react-router-dom';
 import { RenderResult, render } from '@testing-library/react';
 import { createSpecializedApp } from '@backstage/frontend-app-api';
 import {
   ExtensionDefinition,
   IconComponent,
-  IdentityApi,
   RouteRef,
-  configApiRef,
   coreExtensionData,
-  createAppRootWrapperExtension,
   createExtension,
   createExtensionInput,
   createExtensionOverrides,
   createNavItemExtension,
-  useApi,
+  createRouterExtension,
   useRouteRef,
 } from '@backstage/frontend-plugin-api';
 import { MockConfigApi } from '@backstage/test-utils';
@@ -44,15 +35,7 @@ import { JsonArray, JsonObject, JsonValue } from '@backstage/types';
 // 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 { createSignInPageExtension } from '../../../frontend-plugin-api/src/extensions/createSignInPageExtension';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { toInternalExtensionDefinition } from '../../../frontend-plugin-api/src/wiring/createExtension';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { InternalAppContext } from '../../../frontend-app-api/src/wiring/InternalAppContext';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { SignInPageProps } from '../../../core-plugin-api';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { getBasePath } from '../../../core-app-api/src/app/AppRouter';
 
 const NavItem = (props: {
   routeRef: RouteRef<undefined>;
@@ -102,113 +85,6 @@ const TestAppNavExtension = createExtension({
   },
 });
 
-const AuthenticationProvider = (props: {
-  signInPage?: ComponentType<SignInPageProps>;
-  children: ReactNode;
-}) => {
-  const { signInPage: SignInPage, children } = props;
-  const configApi = useApi(configApiRef);
-  const signOutTargetUrl = getBasePath(configApi) || '/';
-
-  const internalAppContext = useContext(InternalAppContext);
-  if (!internalAppContext) {
-    throw new Error('AppRouter must be rendered within the AppProvider');
-  }
-
-  const { appIdentityProxy } = internalAppContext;
-  const [identityApi, setIdentityApi] = useState<IdentityApi>();
-
-  if (!SignInPage) {
-    appIdentityProxy.setTarget(
-      {
-        getUserId: () => 'guest',
-        getIdToken: async () => undefined,
-        getProfile: () => ({
-          email: 'guest@example.com',
-          displayName: 'Guest',
-        }),
-        getProfileInfo: async () => ({
-          email: 'guest@example.com',
-          displayName: 'Guest',
-        }),
-        getBackstageIdentity: async () => ({
-          type: 'user',
-          userEntityRef: 'user:default/guest',
-          ownershipEntityRefs: ['user:default/guest'],
-        }),
-        getCredentials: async () => ({}),
-        signOut: async () => {},
-      },
-      { signOutTargetUrl },
-    );
-
-    return children;
-  }
-
-  if (!identityApi) {
-    return <SignInPage onSignInSuccess={setIdentityApi} />;
-  }
-
-  appIdentityProxy.setTarget(identityApi, {
-    signOutTargetUrl,
-  });
-
-  return children;
-};
-
-const TestAppRootExtension = createExtension({
-  namespace: 'app',
-  name: 'root',
-  attachTo: { id: 'app', input: 'root' },
-  inputs: {
-    signInPage: createExtensionInput(
-      { component: createSignInPageExtension.componentDataRef },
-      { singleton: true, optional: true },
-    ),
-    children: createExtensionInput(
-      { element: coreExtensionData.reactElement },
-      { singleton: true },
-    ),
-    elements: createExtensionInput(
-      { element: coreExtensionData.reactElement },
-      { optional: true },
-    ),
-    wrappers: createExtensionInput(
-      { component: createAppRootWrapperExtension.componentDataRef },
-      { optional: true },
-    ),
-  },
-  output: {
-    element: coreExtensionData.reactElement,
-  },
-  factory({ inputs }) {
-    const SignInPage = inputs.signInPage?.output.component;
-
-    let content: React.ReactNode = (
-      <>
-        {inputs.elements.map(el => (
-          <Fragment key={el.node.spec.id}>{el.output.element}</Fragment>
-        ))}
-        {inputs.children.output.element}
-      </>
-    );
-
-    for (const wrapper of inputs.wrappers) {
-      content = <wrapper.output.component>{content}</wrapper.output.component>;
-    }
-
-    return {
-      element: (
-        <MemoryRouter>
-          <AuthenticationProvider signInPage={SignInPage}>
-            {content}
-          </AuthenticationProvider>
-        </MemoryRouter>
-      ),
-    };
-  },
-});
-
 /** @public */
 export class ExtensionTester {
   /** @internal */
@@ -302,7 +178,12 @@ export class ExtensionTester {
           extensions: [
             ...this.#extensions.map(extension => extension.definition),
             TestAppNavExtension,
-            TestAppRootExtension,
+            createRouterExtension({
+              namespace: 'test',
+              Component: ({ children }) => (
+                <MemoryRouter>{children}</MemoryRouter>
+              ),
+            }),
           ],
         }),
       ],
diff --git a/packages/frontend-test-utils/src/app/renderInTestApp.test.tsx b/packages/frontend-test-utils/src/app/renderInTestApp.test.tsx
index a6783d43a3..a56ae2f140 100644
--- a/packages/frontend-test-utils/src/app/renderInTestApp.test.tsx
+++ b/packages/frontend-test-utils/src/app/renderInTestApp.test.tsx
@@ -56,9 +56,13 @@ describe('renderInTestApp', () => {
 
     fireEvent.click(screen.getByRole('link', { name: 'See details' }));
 
-    expect(analyticsApiMock.getEvents()[0]).toMatchObject({
-      action: 'click',
-      subject: 'See details',
-    });
+    expect(analyticsApiMock.getEvents()).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          action: 'click',
+          subject: 'See details',
+        }),
+      ]),
+    );
   });
 });