diff --git a/packages/api-fetch/src/core.js b/packages/api-fetch/src/core.js
index 1fb58fc6b8bd85..4f41de7889e470 100644
--- a/packages/api-fetch/src/core.js
+++ b/packages/api-fetch/src/core.js
@@ -6,10 +6,6 @@
 /**
  * Internal dependencies
  */
-import fetchAllMiddleware from './middlewares/fetch-all-middleware';
-import namespaceEndpointMiddleware from './middlewares/namespace-endpoint';
-import httpV1Middleware from './middlewares/http-v1';
-import userLocaleMiddleware from './middlewares/user-locale';
 import {
 	parseResponseAndNormalizeError,
 	parseAndThrowError,
@@ -39,28 +35,6 @@ const DEFAULT_OPTIONS = {
 	credentials: 'include',
 };
 
-/** @typedef {import('./types').APIFetchMiddleware} APIFetchMiddleware */
-/** @typedef {import('./types').APIFetchOptions} APIFetchOptions */
-
-/**
- * @type {import('./types').APIFetchMiddleware[]}
- */
-const middlewares = [
-	userLocaleMiddleware,
-	namespaceEndpointMiddleware,
-	httpV1Middleware,
-	fetchAllMiddleware,
-];
-
-/**
- * Register a middleware
- *
- * @param {import('./types').APIFetchMiddleware} middleware
- */
-export function registerMiddleware( middleware ) {
-	middlewares.unshift( middleware );
-}
-
 /**
  * Checks the status of a response, throwing the Response as an error if
  * it is outside the 200 range.
@@ -142,12 +116,19 @@ export function setFetchHandler( newFetchHandler ) {
 	fetchHandler = newFetchHandler;
 }
 
+/** @type { typeof import('./middlewares/singleton').middlewares } */
+let middlewares;
+
 /**
  * @template T
  * @param {import('./types').APIFetchOptions} options
  * @return {Promise<T>} A promise representing the request processed via the registered middlewares.
  */
-export function apiFetch( options ) {
+export async function apiFetch( options ) {
+	if ( ! middlewares ) {
+		middlewares = ( await import( './middlewares/singleton' ) ).middlewares;
+	}
+
 	// creates a nested function chain that calls all middlewares and finally the `fetchHandler`,
 	// converting `middlewares = [ m1, m2, m3 ]` into:
 	// ```
diff --git a/packages/api-fetch/src/index.ts b/packages/api-fetch/src/index.ts
index b211ec9032889f..78b621a200e808 100644
--- a/packages/api-fetch/src/index.ts
+++ b/packages/api-fetch/src/index.ts
@@ -1,18 +1,19 @@
 /**
  * Internal dependencies
  */
-import createNonceMiddleware from './middlewares/nonce';
-import createRootURLMiddleware from './middlewares/root-url';
-import createPreloadingMiddleware from './middlewares/preloading';
-import fetchAllMiddleware from './middlewares/fetch-all-middleware';
-import mediaUploadMiddleware from './middlewares/media-upload';
-import createThemePreviewMiddleware from './middlewares/theme-preview';
+import { createNonceMiddleware } from './middlewares/nonce';
+import { createRootURLMiddleware } from './middlewares/root-url';
+import { createPreloadingMiddleware } from './middlewares/preloading';
+import { fetchAllMiddleware } from './middlewares/fetch-all-middleware';
+import { mediaUploadMiddleware } from './middlewares/media-upload';
+import { createThemePreviewMiddleware } from './middlewares/theme-preview';
 import * as ApiFetchCore from './core';
 import { type APIFetchOptions } from './types';
+import { registerMiddleware } from './middlewares/singleton';
 
 export interface ApiFetch {
 	< T >( options: APIFetchOptions ): Promise< T >;
-	use: typeof ApiFetchCore.registerMiddleware;
+	use: typeof registerMiddleware;
 	setFetchHandler: typeof ApiFetchCore.setFetchHandler;
 	createNonceMiddleware: typeof createNonceMiddleware;
 	createPreloadingMiddleware: typeof createPreloadingMiddleware;
@@ -25,7 +26,7 @@ export interface ApiFetch {
 // @ts-expect-error This is an incomplete type we'll add properties to.
 const apiFetch: ApiFetch = ApiFetchCore.apiFetch;
 
-apiFetch.use = ApiFetchCore.registerMiddleware;
+apiFetch.use = registerMiddleware;
 apiFetch.setFetchHandler = ApiFetchCore.setFetchHandler;
 apiFetch.createNonceMiddleware = createNonceMiddleware;
 apiFetch.createPreloadingMiddleware = createPreloadingMiddleware;
diff --git a/packages/api-fetch/src/middlewares/fetch-all-middleware.js b/packages/api-fetch/src/middlewares/fetch-all-middleware.js
index f51c99ae3d2b40..f2ec447a93e266 100644
--- a/packages/api-fetch/src/middlewares/fetch-all-middleware.js
+++ b/packages/api-fetch/src/middlewares/fetch-all-middleware.js
@@ -1,7 +1,7 @@
 /**
  * Internal dependencies
  */
-import apiFetch from '..';
+import { apiFetch } from '../core';
 
 /**
  * Apply query arguments to both URL and Path, whichever is present.
@@ -11,7 +11,7 @@ import apiFetch from '..';
  * @return {import('../types').APIFetchOptions} The request with the modified query args
  */
 const modifyQuery = ( { path, url, ...options }, queryArgs ) => {
-	/** @type {import('../core').APIFetchOptions} */
+	/** @type {import('../types').APIFetchOptions} */
 	const result = {
 		...options,
 	};
@@ -98,7 +98,7 @@ const requestContainsUnboundedQuery = ( options ) => {
  *
  * @type {import('../types').APIFetchMiddleware}
  */
-const fetchAllMiddleware = async ( options, next ) => {
+export const fetchAllMiddleware = async ( options, next ) => {
 	if ( options.parse === false ) {
 		// If a consumer has opted out of parsing, do not apply middleware.
 		return next( options );
@@ -148,5 +148,3 @@ const fetchAllMiddleware = async ( options, next ) => {
 	}
 	return mergedResults;
 };
-
-export default fetchAllMiddleware;
diff --git a/packages/api-fetch/src/middlewares/http-v1.js b/packages/api-fetch/src/middlewares/http-v1.js
index 953fc26ff70c8a..78daf62282ab74 100644
--- a/packages/api-fetch/src/middlewares/http-v1.js
+++ b/packages/api-fetch/src/middlewares/http-v1.js
@@ -23,7 +23,7 @@ const DEFAULT_METHOD = 'GET';
  *
  * @type {import('../types').APIFetchMiddleware}
  */
-const httpV1Middleware = ( options, next ) => {
+export const httpV1Middleware = ( options, next ) => {
 	const { method = DEFAULT_METHOD } = options;
 	if ( OVERRIDE_METHODS.has( method.toUpperCase() ) ) {
 		options = {
@@ -39,5 +39,3 @@ const httpV1Middleware = ( options, next ) => {
 
 	return next( options );
 };
-
-export default httpV1Middleware;
diff --git a/packages/api-fetch/src/middlewares/media-upload.js b/packages/api-fetch/src/middlewares/media-upload.js
index 365c20a7439469..7aa4df90a4c0ae 100644
--- a/packages/api-fetch/src/middlewares/media-upload.js
+++ b/packages/api-fetch/src/middlewares/media-upload.js
@@ -29,7 +29,7 @@ function isMediaUploadRequest( options ) {
  *
  * @type {import('../types').APIFetchMiddleware}
  */
-const mediaUploadMiddleware = ( options, next ) => {
+export const mediaUploadMiddleware = ( options, next ) => {
 	if ( ! isMediaUploadRequest( options ) ) {
 		return next( options );
 	}
@@ -89,5 +89,3 @@ const mediaUploadMiddleware = ( options, next ) => {
 			parseResponseAndNormalizeError( response, options.parse )
 		);
 };
-
-export default mediaUploadMiddleware;
diff --git a/packages/api-fetch/src/middlewares/namespace-endpoint.js b/packages/api-fetch/src/middlewares/namespace-endpoint.js
index bfb0e824187f35..260caf89c7ef79 100644
--- a/packages/api-fetch/src/middlewares/namespace-endpoint.js
+++ b/packages/api-fetch/src/middlewares/namespace-endpoint.js
@@ -1,7 +1,7 @@
 /**
  * @type {import('../types').APIFetchMiddleware}
  */
-const namespaceAndEndpointMiddleware = ( options, next ) => {
+export const namespaceEndpointMiddleware = ( options, next ) => {
 	let path = options.path;
 	let namespaceTrimmed, endpointTrimmed;
 
@@ -26,5 +26,3 @@ const namespaceAndEndpointMiddleware = ( options, next ) => {
 		path,
 	} );
 };
-
-export default namespaceAndEndpointMiddleware;
diff --git a/packages/api-fetch/src/middlewares/nonce.js b/packages/api-fetch/src/middlewares/nonce.js
index 60914823661ed9..21e432bb4aa9aa 100644
--- a/packages/api-fetch/src/middlewares/nonce.js
+++ b/packages/api-fetch/src/middlewares/nonce.js
@@ -2,7 +2,7 @@
  * @param {string} nonce
  * @return {import('../types').APIFetchMiddleware & { nonce: string }} A middleware to enhance a request with a nonce.
  */
-function createNonceMiddleware( nonce ) {
+export function createNonceMiddleware( nonce ) {
 	/**
 	 * @type {import('../types').APIFetchMiddleware & { nonce: string }}
 	 */
@@ -33,5 +33,3 @@ function createNonceMiddleware( nonce ) {
 
 	return middleware;
 }
-
-export default createNonceMiddleware;
diff --git a/packages/api-fetch/src/middlewares/preloading.js b/packages/api-fetch/src/middlewares/preloading.js
index dac1228866520d..90bdf07fa5e1bd 100644
--- a/packages/api-fetch/src/middlewares/preloading.js
+++ b/packages/api-fetch/src/middlewares/preloading.js
@@ -6,7 +6,7 @@
  * @param {Record<string, any>} preloadedData
  * @return {import('../types').APIFetchMiddleware} Preloading middleware.
  */
-function createPreloadingMiddleware( preloadedData ) {
+export function createPreloadingMiddleware( preloadedData ) {
 	const cache = Object.fromEntries(
 		Object.entries( preloadedData ).map( ( [ path, data ] ) => [
 			path,
@@ -68,5 +68,3 @@ function prepareResponse( responseData, parse ) {
 			  } )
 	);
 }
-
-export default createPreloadingMiddleware;
diff --git a/packages/api-fetch/src/middlewares/root-url.js b/packages/api-fetch/src/middlewares/root-url.js
index cde855f3f9504f..9b522ee481bcb5 100644
--- a/packages/api-fetch/src/middlewares/root-url.js
+++ b/packages/api-fetch/src/middlewares/root-url.js
@@ -1,14 +1,14 @@
 /**
  * Internal dependencies
  */
-import namespaceAndEndpointMiddleware from './namespace-endpoint';
+import { namespaceEndpointMiddleware } from './namespace-endpoint';
 
 /**
  * @param {string} rootURL
  * @return {import('../types').APIFetchMiddleware} Root URL middleware.
  */
-const createRootURLMiddleware = ( rootURL ) => ( options, next ) => {
-	return namespaceAndEndpointMiddleware( options, ( optionsWithPath ) => {
+export const createRootURLMiddleware = ( rootURL ) => ( options, next ) => {
+	return namespaceEndpointMiddleware( options, ( optionsWithPath ) => {
 		let url = optionsWithPath.url;
 		let path = optionsWithPath.path;
 		let apiRoot;
@@ -40,5 +40,3 @@ const createRootURLMiddleware = ( rootURL ) => ( options, next ) => {
 		} );
 	} );
 };
-
-export default createRootURLMiddleware;
diff --git a/packages/api-fetch/src/middlewares/singleton.js b/packages/api-fetch/src/middlewares/singleton.js
new file mode 100644
index 00000000000000..48fc4ff23b6cd3
--- /dev/null
+++ b/packages/api-fetch/src/middlewares/singleton.js
@@ -0,0 +1,26 @@
+/**
+ * Internal dependencies
+ */
+import { fetchAllMiddleware } from './fetch-all-middleware';
+import { namespaceEndpointMiddleware } from './namespace-endpoint';
+import { httpV1Middleware } from './http-v1';
+import { userLocaleMiddleware } from './user-locale';
+
+/**
+ * @type {import('../types').APIFetchMiddleware[]}
+ */
+export const middlewares = [
+	userLocaleMiddleware,
+	namespaceEndpointMiddleware,
+	httpV1Middleware,
+	fetchAllMiddleware,
+];
+
+/**
+ * Register a middleware
+ *
+ * @param {import('../types').APIFetchMiddleware} middleware
+ */
+export function registerMiddleware( middleware ) {
+	middlewares.unshift( middleware );
+}
diff --git a/packages/api-fetch/src/middlewares/theme-preview.js b/packages/api-fetch/src/middlewares/theme-preview.js
index c0b928eb2a3b8e..7f332120cc2a97 100644
--- a/packages/api-fetch/src/middlewares/theme-preview.js
+++ b/packages/api-fetch/src/middlewares/theme-preview.js
@@ -11,8 +11,6 @@
  *
  * @return {import('../types').APIFetchMiddleware} Preloading middleware.
  */
-const createThemePreviewMiddleware = () => ( options, next ) => {
+export const createThemePreviewMiddleware = () => ( options, next ) => {
 	return next( options );
 };
-
-export default createThemePreviewMiddleware;
diff --git a/packages/api-fetch/src/middlewares/user-locale.js b/packages/api-fetch/src/middlewares/user-locale.js
index 0546e61003fcf8..9b6eae44e46730 100644
--- a/packages/api-fetch/src/middlewares/user-locale.js
+++ b/packages/api-fetch/src/middlewares/user-locale.js
@@ -5,8 +5,6 @@
 /**
  * @type {import('../types').APIFetchMiddleware}
  */
-const userLocaleMiddleware = ( options, next ) => {
+export const userLocaleMiddleware = ( options, next ) => {
 	return next( options );
 };
-
-export default userLocaleMiddleware;
diff --git a/packages/api-fetch/src/wp-module.js b/packages/api-fetch/src/wp-module.js
index da2150b5d64850..7e71670c006e81 100644
--- a/packages/api-fetch/src/wp-module.js
+++ b/packages/api-fetch/src/wp-module.js
@@ -1,16 +1,19 @@
 /**
  * Internal dependencies
  */
-import createNonceMiddleware from './middlewares/nonce';
-import createRootURLMiddleware from './middlewares/root-url';
-import createPreloadingMiddleware from './middlewares/preloading';
-import fetchAllMiddleware from './middlewares/fetch-all-middleware';
-import mediaUploadMiddleware from './middlewares/media-upload';
-import createThemePreviewMiddleware from './middlewares/theme-preview';
-import { apiFetch, registerMiddleware, setFetchHandler } from './core';
+import { createNonceMiddleware } from './middlewares/nonce';
+import { createRootURLMiddleware } from './middlewares/root-url';
+import { createPreloadingMiddleware } from './middlewares/preloading';
+import { fetchAllMiddleware } from './middlewares/fetch-all-middleware';
+import { mediaUploadMiddleware } from './middlewares/media-upload';
+import { createThemePreviewMiddleware } from './middlewares/theme-preview';
+import { apiFetch, setFetchHandler } from './core';
+import { registerMiddleware } from './middlewares/singleton';
 
 if ( typeof document !== 'undefined' ) {
-	const el = document.getElementById( 'scriptmoduledata_@wordpress/api-fetch' );
+	const el = document.getElementById(
+		'wp-scriptmodule-data_@wordpress/api-fetch'
+	);
 	if ( el?.textContent ) {
 		console.group( 'api-fetch init' );
 		try {
@@ -34,15 +37,18 @@ if ( typeof document !== 'undefined' ) {
 				apiFetch.nonceEndpoint = config.nonceEndpoint;
 			}
 			if ( config.themePreviewPath ) {
-				// @ts-expect-error This is wrong, done for testing.
-				registerMiddleware( createThemePreviewMiddleware( config.themePreviewPath ) );
+				registerMiddleware(
+					// @ts-expect-error This is wrong, done for testing.
+					createThemePreviewMiddleware( config.themePreviewPath )
+				);
 			}
 			if ( config.preloadData ) {
-				registerMiddleware( createPreloadingMiddleware( config.preloadData ) );
+				registerMiddleware(
+					createPreloadingMiddleware( config.preloadData )
+				);
 			}
-
-		} catch {
-			console.error( 'error' );
+		} catch ( err ) {
+			console.error( err );
 		} finally {
 			console.groupEnd();
 		}