diff --git a/scripts/moduleReport.js b/scripts/moduleReport.js
index ee5cadf0a8..f82a58ea8a 100644
--- a/scripts/moduleReport.js
+++ b/scripts/moduleReport.js
@@ -9,6 +9,8 @@ const moduleNames = [
   'XHRPolling',
   'XHRStreaming',
   'WebSocketTransport',
+  'XHRRequest',
+  'FetchRequest',
 ];
 
 // List of all free-standing functions exported by the library along with the
diff --git a/src/common/lib/client/baseclient.ts b/src/common/lib/client/baseclient.ts
index fbb2be3475..ddc726b4d5 100644
--- a/src/common/lib/client/baseclient.ts
+++ b/src/common/lib/client/baseclient.ts
@@ -15,6 +15,7 @@ import { Rest } from './rest';
 import { IUntypedCryptoStatic } from 'common/types/ICryptoStatic';
 import { throwMissingModuleError } from '../util/utils';
 import { MsgPack } from 'common/types/msgpack';
+import { HTTPRequestImplementations } from 'platform/web/lib/http/http';
 
 type BatchResult<T> = API.Types.BatchResult<T>;
 type BatchPublishSpec = API.Types.BatchPublishSpec;
@@ -41,8 +42,12 @@ class BaseClient {
   private readonly _rest: Rest | null;
   readonly _Crypto: IUntypedCryptoStatic | null;
   readonly _MsgPack: MsgPack | null;
+  // Extra HTTP request implementations available to this client, in addition to those in web’s Http.bundledRequestImplementations
+  readonly _additionalHTTPRequestImplementations: HTTPRequestImplementations;
 
   constructor(options: ClientOptions | string, modules: ModulesMap) {
+    this._additionalHTTPRequestImplementations = modules;
+
     if (!options) {
       const msg = 'no options provided';
       Logger.logAction(Logger.LOG_ERROR, 'BaseClient()', msg);
diff --git a/src/common/lib/client/modulesmap.ts b/src/common/lib/client/modulesmap.ts
index ada7de44ee..dff32a69e4 100644
--- a/src/common/lib/client/modulesmap.ts
+++ b/src/common/lib/client/modulesmap.ts
@@ -3,6 +3,8 @@ import { IUntypedCryptoStatic } from '../../types/ICryptoStatic';
 import { MsgPack } from 'common/types/msgpack';
 import RealtimePresence from './realtimepresence';
 import { TransportInitialiser } from '../transport/connectionmanager';
+import XHRRequest from 'platform/web/lib/http/request/xhrrequest';
+import fetchRequest from 'platform/web/lib/http/request/fetchrequest';
 
 export interface ModulesMap {
   Rest?: typeof Rest;
@@ -12,6 +14,8 @@ export interface ModulesMap {
   WebSocketTransport?: TransportInitialiser;
   XHRPolling?: TransportInitialiser;
   XHRStreaming?: TransportInitialiser;
+  XHRRequest?: typeof XHRRequest;
+  FetchRequest?: typeof fetchRequest;
 }
 
 export const allCommonModules: ModulesMap = { Rest };
diff --git a/src/platform/nativescript/index.ts b/src/platform/nativescript/index.ts
index c8354aa69d..119fdcb048 100644
--- a/src/platform/nativescript/index.ts
+++ b/src/platform/nativescript/index.ts
@@ -19,6 +19,7 @@ import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from './lib/util/webstorage';
 import PlatformDefaults from '../web/lib/util/defaults';
 import msgpack from '../web/lib/util/msgpack';
+import { defaultBundledRequestImplementations } from '../web/lib/http/request';
 
 const Crypto = createCryptoClass(Config, BufferUtils);
 
@@ -34,6 +35,8 @@ for (const clientClass of [DefaultRest, DefaultRealtime]) {
   clientClass._MsgPack = msgpack;
 }
 
+Http.bundledRequestImplementations = defaultBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
diff --git a/src/platform/react-native/index.ts b/src/platform/react-native/index.ts
index dc27bb62c8..e0539aa92a 100644
--- a/src/platform/react-native/index.ts
+++ b/src/platform/react-native/index.ts
@@ -17,6 +17,7 @@ import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from '../web/lib/util/webstorage';
 import PlatformDefaults from '../web/lib/util/defaults';
 import msgpack from '../web/lib/util/msgpack';
+import { defaultBundledRequestImplementations } from '../web/lib/http/request';
 
 const Config = configFactory(BufferUtils);
 
@@ -34,6 +35,8 @@ for (const clientClass of [DefaultRest, DefaultRealtime]) {
   clientClass._MsgPack = msgpack;
 }
 
+Http.bundledRequestImplementations = defaultBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
diff --git a/src/platform/web-noencryption/index.ts b/src/platform/web-noencryption/index.ts
index dcb4120123..64dcf02b5e 100644
--- a/src/platform/web-noencryption/index.ts
+++ b/src/platform/web-noencryption/index.ts
@@ -16,6 +16,7 @@ import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from '../web/lib/util/webstorage';
 import PlatformDefaults from '../web/lib/util/defaults';
 import msgpack from '../web/lib/util/msgpack';
+import { defaultBundledRequestImplementations } from '../web/lib/http/request';
 
 Platform.Crypto = null;
 Platform.BufferUtils = BufferUtils;
@@ -28,6 +29,8 @@ for (const clientClass of [DefaultRest, DefaultRealtime]) {
   clientClass._MsgPack = msgpack;
 }
 
+Http.bundledRequestImplementations = defaultBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
diff --git a/src/platform/web/index.ts b/src/platform/web/index.ts
index 3e40e123b7..27d6c9556b 100644
--- a/src/platform/web/index.ts
+++ b/src/platform/web/index.ts
@@ -17,6 +17,7 @@ import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from './lib/util/webstorage';
 import PlatformDefaults from './lib/util/defaults';
 import msgpack from './lib/util/msgpack';
+import { defaultBundledRequestImplementations } from './lib/http/request';
 
 const Crypto = createCryptoClass(Config, BufferUtils);
 
@@ -32,6 +33,8 @@ for (const clientClass of [DefaultRest, DefaultRealtime]) {
   clientClass._MsgPack = msgpack;
 }
 
+Http.bundledRequestImplementations = defaultBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
diff --git a/src/platform/web/lib/http/http.ts b/src/platform/web/lib/http/http.ts
index b8566c5633..626a946758 100644
--- a/src/platform/web/lib/http/http.ts
+++ b/src/platform/web/lib/http/http.ts
@@ -2,16 +2,17 @@ import Platform from 'common/platform';
 import * as Utils from 'common/lib/util/utils';
 import Defaults from 'common/lib/util/defaults';
 import ErrorInfo, { PartialErrorInfo } from 'common/lib/types/errorinfo';
-import { IHttpStatic, RequestCallback, RequestParams } from 'common/types/http';
+import { RequestCallback, RequestParams } from 'common/types/http';
 import HttpMethods from 'common/constants/HttpMethods';
 import BaseClient from 'common/lib/client/baseclient';
 import BaseRealtime from 'common/lib/client/baserealtime';
-import XHRRequest from './request/xhrrequest';
 import XHRStates from 'common/constants/XHRStates';
 import Logger from 'common/lib/util/logger';
 import { StandardCallback } from 'common/types/utils';
-import fetchRequest from './request/fetchrequest';
 import { isSuccessCode } from 'common/constants/HttpStatusCodes';
+import { ModulesMap } from 'common/lib/client/modulesmap';
+
+export type HTTPRequestImplementations = Pick<ModulesMap, 'XHRRequest' | 'FetchRequest'>;
 
 function shouldFallback(errorInfo: ErrorInfo) {
   const statusCode = errorInfo.statusCode as number;
@@ -39,10 +40,20 @@ function getHosts(client: BaseClient): string[] {
   return Defaults.getHosts(client.options);
 }
 
-const Http: IHttpStatic = class {
+function createMissingImplementationError() {
+  return new ErrorInfo(
+    'No HTTP request module provided. Provide at least one of the FetchRequest or XHRRequest modules.',
+    400,
+    40000
+  );
+}
+
+const Http = class {
   static methods = [HttpMethods.Get, HttpMethods.Delete, HttpMethods.Post, HttpMethods.Put, HttpMethods.Patch];
   static methodsWithoutBody = [HttpMethods.Get, HttpMethods.Delete];
   static methodsWithBody = [HttpMethods.Post, HttpMethods.Put, HttpMethods.Patch];
+  // HTTP request implementations that are available even without a BaseClient object (needed by some tests which directly instantiate `Http` without a client)
+  static bundledRequestImplementations: HTTPRequestImplementations;
   checksInProgress: Array<StandardCallback<boolean>> | null = null;
   private client: BaseClient | null;
 
@@ -51,7 +62,20 @@ const Http: IHttpStatic = class {
     const connectivityCheckUrl = client?.options.connectivityCheckUrl || Defaults.connectivityCheckUrl;
     const connectivityCheckParams = client?.options.connectivityCheckParams ?? null;
     const connectivityUrlIsDefault = !client?.options.connectivityCheckUrl;
-    if (Platform.Config.xhrSupported) {
+
+    const requestImplementations = {
+      ...Http.bundledRequestImplementations,
+      ...client?._additionalHTTPRequestImplementations,
+    };
+    const xhrRequestImplementation = requestImplementations.XHRRequest;
+    const fetchRequestImplementation = requestImplementations.FetchRequest;
+    const hasImplementation = !!(xhrRequestImplementation || fetchRequestImplementation);
+
+    if (!hasImplementation) {
+      throw createMissingImplementationError();
+    }
+
+    if (Platform.Config.xhrSupported && xhrRequestImplementation) {
       this.supportsAuthHeaders = true;
       this.Request = function (
         method: HttpMethods,
@@ -61,7 +85,7 @@ const Http: IHttpStatic = class {
         body: unknown,
         callback: RequestCallback
       ) {
-        const req = XHRRequest.createRequest(
+        const req = xhrRequestImplementation.createRequest(
           uri,
           headers,
           params,
@@ -104,10 +128,10 @@ const Http: IHttpStatic = class {
           );
         };
       }
-    } else if (Platform.Config.fetchSupported) {
+    } else if (Platform.Config.fetchSupported && fetchRequestImplementation) {
       this.supportsAuthHeaders = true;
       this.Request = (method, uri, headers, params, body, callback) => {
-        fetchRequest(method, client ?? null, uri, headers, params, body, callback);
+        fetchRequestImplementation(method, client ?? null, uri, headers, params, body, callback);
       };
       this.checkConnectivity = function (callback: (err: ErrorInfo | null, connectivity: boolean) => void) {
         Logger.logAction(Logger.LOG_MICRO, '(Fetch)Http.checkConnectivity()', 'Sending; ' + connectivityCheckUrl);
@@ -119,7 +143,10 @@ const Http: IHttpStatic = class {
       };
     } else {
       this.Request = (method, uri, headers, params, body, callback) => {
-        callback(new PartialErrorInfo('no supported HTTP transports available', null, 400), null);
+        const error = hasImplementation
+          ? new PartialErrorInfo('no supported HTTP transports available', null, 400)
+          : createMissingImplementationError();
+        callback(error, null);
       };
     }
   }
diff --git a/src/platform/web/lib/http/request/index.ts b/src/platform/web/lib/http/request/index.ts
new file mode 100644
index 0000000000..4fccec5b3b
--- /dev/null
+++ b/src/platform/web/lib/http/request/index.ts
@@ -0,0 +1,10 @@
+import { HTTPRequestImplementations } from '../http';
+import XHRRequest from './xhrrequest';
+import fetchRequest from './fetchrequest';
+
+export const defaultBundledRequestImplementations: HTTPRequestImplementations = {
+  XHRRequest: XHRRequest,
+  FetchRequest: fetchRequest,
+};
+
+export const modulesBundledRequestImplementations: HTTPRequestImplementations = {};
diff --git a/src/platform/web/modules.ts b/src/platform/web/modules.ts
index f9ee3a521d..e12ede52e7 100644
--- a/src/platform/web/modules.ts
+++ b/src/platform/web/modules.ts
@@ -15,6 +15,7 @@ import Logger from '../../common/lib/util/logger';
 import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from './lib/util/webstorage';
 import PlatformDefaults from './lib/util/defaults';
+import { modulesBundledRequestImplementations } from './lib/http/request';
 
 Platform.BufferUtils = BufferUtils;
 Platform.Http = Http;
@@ -22,6 +23,8 @@ Platform.Config = Config;
 Platform.Transports = ModulesTransports;
 Platform.WebStorage = WebStorage;
 
+Http.bundledRequestImplementations = modulesBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
@@ -45,5 +48,6 @@ export * from './modules/presencemessage';
 export * from './modules/msgpack';
 export * from './modules/realtimepresence';
 export * from './modules/transports';
+export * from './modules/http';
 export { Rest } from '../../common/lib/client/rest';
 export { BaseRest, BaseRealtime, ErrorInfo };
diff --git a/src/platform/web/modules/http.ts b/src/platform/web/modules/http.ts
new file mode 100644
index 0000000000..24b664f30d
--- /dev/null
+++ b/src/platform/web/modules/http.ts
@@ -0,0 +1,2 @@
+export { default as XHRRequest } from '../lib/http/request/xhrrequest';
+export { default as FetchRequest } from '../lib/http/request/fetchrequest';
diff --git a/test/browser/modules.test.js b/test/browser/modules.test.js
index efaf654b3b..d73b76624e 100644
--- a/test/browser/modules.test.js
+++ b/test/browser/modules.test.js
@@ -17,6 +17,8 @@ import {
   XHRPolling,
   XHRStreaming,
   WebSocketTransport,
+  FetchRequest,
+  XHRRequest,
 } from '../../build/modules/index.js';
 
 describe('browser/modules', function () {
@@ -45,23 +47,21 @@ describe('browser/modules', function () {
   });
 
   describe('without any modules', () => {
-    describe('BaseRest', () => {
-      it('can be constructed', () => {
-        expect(() => new BaseRest(ablyClientOptions(), {})).not.to.throw();
-      });
-    });
-
-    describe('BaseRealtime', () => {
-      it('throws an error due to absence of a transport module', () => {
-        expect(() => new BaseRealtime(ablyClientOptions(), {})).to.throw('no requested transports available');
+    for (const clientClass of [BaseRest, BaseRealtime]) {
+      describe(clientClass.name, () => {
+        it('throws an error due to the absence of an HTTP module', () => {
+          expect(() => new clientClass(ablyClientOptions(), {})).to.throw(
+            'No HTTP request module provided. Provide at least one of the FetchRequest or XHRRequest modules.'
+          );
+        });
       });
-    });
+    }
   });
 
   describe('Rest', () => {
     describe('BaseRest without explicit Rest', () => {
       it('offers REST functionality', async () => {
-        const client = new BaseRest(ablyClientOptions(), {});
+        const client = new BaseRest(ablyClientOptions(), { FetchRequest });
         const time = await client.time();
         expect(time).to.be.a('number');
       });
@@ -69,7 +69,7 @@ describe('browser/modules', function () {
 
     describe('BaseRealtime with Rest', () => {
       it('offers REST functionality', async () => {
-        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport, Rest });
+        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport, FetchRequest, Rest });
         const time = await client.time();
         expect(time).to.be.a('number');
       });
@@ -77,7 +77,7 @@ describe('browser/modules', function () {
 
     describe('BaseRealtime without Rest', () => {
       it('throws an error when attempting to use REST functionality', async () => {
-        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport });
+        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport, FetchRequest });
         expect(() => client.time()).to.throw('Rest module not provided');
       });
     });
@@ -214,10 +214,10 @@ describe('browser/modules', function () {
   describe('Crypto', () => {
     describe('without Crypto', () => {
       async function testThrowsAnErrorWhenGivenChannelOptionsWithACipher(clientClassConfig) {
-        const client = new clientClassConfig.clientClass(
-          ablyClientOptions(),
-          clientClassConfig.additionalModules ?? {}
-        );
+        const client = new clientClassConfig.clientClass(ablyClientOptions(), {
+          ...clientClassConfig.additionalModules,
+          FetchRequest,
+        });
         const key = await generateRandomKey();
         expect(() => client.channels.get('channel', { cipher: { key } })).to.throw('Crypto module not provided');
       }
@@ -242,7 +242,7 @@ describe('browser/modules', function () {
 
         // Publish the message on a channel configured to use encryption, and receive it on one not configured to use encryption
 
-        const rxClient = new BaseRealtime(clientOptions, { WebSocketTransport });
+        const rxClient = new BaseRealtime(clientOptions, { WebSocketTransport, FetchRequest });
         const rxChannel = rxClient.channels.get('channel');
         await rxChannel.attach();
 
@@ -252,7 +252,8 @@ describe('browser/modules', function () {
 
         const txMessage = { name: 'message', data: 'data' };
         const txClient = new clientClassConfig.clientClass(clientOptions, {
-          ...(clientClassConfig.additionalModules ?? {}),
+          ...clientClassConfig.additionalModules,
+          FetchRequest,
           Crypto,
         });
         const txChannel = txClient.channels.get('channel', encryptionChannelOptions);
@@ -318,7 +319,7 @@ describe('browser/modules', function () {
       describe('without MsgPack', () => {
         describe('BaseRest', () => {
           it('uses JSON', async () => {
-            const client = new BaseRest(ablyClientOptions({ useBinaryProtocol: true }), {});
+            const client = new BaseRest(ablyClientOptions({ useBinaryProtocol: true }), { FetchRequest });
             await testRestUsesContentType(client, 'application/json');
           });
         });
@@ -327,6 +328,7 @@ describe('browser/modules', function () {
           it('uses JSON', async () => {
             const client = new BaseRealtime(ablyClientOptions({ useBinaryProtocol: true, autoConnect: false }), {
               WebSocketTransport,
+              FetchRequest,
             });
             await testRealtimeUsesFormat(client, 'json');
           });
@@ -337,6 +339,7 @@ describe('browser/modules', function () {
         describe('BaseRest', () => {
           it('uses MessagePack', async () => {
             const client = new BaseRest(ablyClientOptions({ useBinaryProtocol: true }), {
+              FetchRequest,
               MsgPack,
             });
             await testRestUsesContentType(client, 'application/x-msgpack');
@@ -347,6 +350,7 @@ describe('browser/modules', function () {
           it('uses MessagePack', async () => {
             const client = new BaseRealtime(ablyClientOptions({ useBinaryProtocol: true, autoConnect: false }), {
               WebSocketTransport,
+              FetchRequest,
               MsgPack,
             });
             await testRealtimeUsesFormat(client, 'msgpack');
@@ -359,7 +363,7 @@ describe('browser/modules', function () {
   describe('RealtimePresence', () => {
     describe('BaseRealtime without RealtimePresence', () => {
       it('throws an error when attempting to access the `presence` property', () => {
-        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport });
+        const client = new BaseRealtime(ablyClientOptions(), { WebSocketTransport, FetchRequest });
         const channel = client.channels.get('channel');
 
         expect(() => channel.presence).to.throw('RealtimePresence module not provided');
@@ -368,12 +372,15 @@ describe('browser/modules', function () {
 
     describe('BaseRealtime with RealtimePresence', () => {
       it('offers realtime presence functionality', async () => {
-        const rxChannel = new BaseRealtime(ablyClientOptions(), { WebSocketTransport, RealtimePresence }).channels.get(
-          'channel'
-        );
+        const rxChannel = new BaseRealtime(ablyClientOptions(), {
+          WebSocketTransport,
+          FetchRequest,
+          RealtimePresence,
+        }).channels.get('channel');
         const txClientId = randomString();
         const txChannel = new BaseRealtime(ablyClientOptions({ clientId: txClientId }), {
           WebSocketTransport,
+          FetchRequest,
           RealtimePresence,
         }).channels.get('channel');
 
@@ -435,6 +442,14 @@ describe('browser/modules', function () {
 
   describe('Transports', () => {
     describe('BaseRealtime', () => {
+      describe('without a transport module', () => {
+        it('throws an error due to absence of a transport module', () => {
+          expect(() => new BaseRealtime(ablyClientOptions(), { FetchRequest })).to.throw(
+            'no requested transports available'
+          );
+        });
+      });
+
       for (const scenario of [
         { moduleMapKey: 'WebSocketTransport', transportModule: WebSocketTransport, transportName: 'web_socket' },
         { moduleMapKey: 'XHRPolling', transportModule: XHRPolling, transportName: 'xhr_polling' },
@@ -445,6 +460,7 @@ describe('browser/modules', function () {
             const realtime = new BaseRealtime(
               ablyClientOptions({ autoConnect: false, transports: [scenario.transportName] }),
               {
+                FetchRequest,
                 [scenario.moduleMapKey]: scenario.transportModule,
               }
             );
@@ -468,4 +484,24 @@ describe('browser/modules', function () {
       }
     });
   });
+
+  describe('HTTP request implementations', () => {
+    describe('with multiple HTTP request implementations', () => {
+      it('prefers XHR', async () => {
+        let usedXHR = false;
+
+        const XHRRequestSpy = class XHRRequestSpy extends XHRRequest {
+          static createRequest(...args) {
+            usedXHR = true;
+            return super.createRequest(...args);
+          }
+        };
+
+        const rest = new BaseRest(ablyClientOptions(), { FetchRequest, XHRRequest: XHRRequestSpy });
+        await rest.time();
+
+        expect(usedXHR).to.be.true;
+      });
+    });
+  });
 });