diff --git a/scripts/moduleReport.js b/scripts/moduleReport.js
index a8937d594b..609a3d1e93 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 72a61f7ff2..ad10a7ae7a 100644
--- a/src/common/lib/client/baseclient.ts
+++ b/src/common/lib/client/baseclient.ts
@@ -14,6 +14,7 @@ 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';
 
 /**
  `BaseClient` acts as the base class for all of the client classes exported by the SDK. It is an implementation detail and this class is not advertised publicly.
@@ -31,8 +32,12 @@ 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 f6a3efed6c..23358f840b 100644
--- a/src/platform/nativescript/index.ts
+++ b/src/platform/nativescript/index.ts
@@ -18,6 +18,7 @@ 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);
 
@@ -33,6 +34,8 @@ 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 35bf6be8b7..bb7defd213 100644
--- a/src/platform/react-native/index.ts
+++ b/src/platform/react-native/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';
 
 const Config = configFactory(BufferUtils);
 
@@ -33,6 +34,8 @@ 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 7864e8e47c..09c1ac50fd 100644
--- a/src/platform/web-noencryption/index.ts
+++ b/src/platform/web-noencryption/index.ts
@@ -15,6 +15,7 @@ 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;
@@ -27,6 +28,8 @@ 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 87c1b40c21..532222f444 100644
--- a/src/platform/web/index.ts
+++ b/src/platform/web/index.ts
@@ -16,6 +16,7 @@ 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);
 
@@ -31,6 +32,8 @@ 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 0b594b1dc9..c901179f36 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 +40,12 @@ function getHosts(client: BaseClient): string[] {
   return Defaults.getHosts(client.options);
 }
 
-const Http: IHttpStatic = class {
+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 +54,15 @@ 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;
+
+    if (Platform.Config.xhrSupported && xhrRequestImplementation) {
       this.supportsAuthHeaders = true;
       this.Request = function (
         method: HttpMethods,
@@ -61,7 +72,7 @@ const Http: IHttpStatic = class {
         body: unknown,
         callback: RequestCallback
       ) {
-        const req = XHRRequest.createRequest(
+        const req = xhrRequestImplementation.createRequest(
           uri,
           headers,
           params,
@@ -104,10 +115,10 @@ 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);
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 c1a2e63e23..e0907b322b 100644
--- a/src/platform/web/modules.ts
+++ b/src/platform/web/modules.ts
@@ -14,6 +14,7 @@ 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;
@@ -21,6 +22,8 @@ Platform.Config = Config;
 Platform.Transports = ModulesTransports;
 Platform.WebStorage = WebStorage;
 
+Http.bundledRequestImplementations = modulesBundledRequestImplementations;
+
 Logger.initLogHandlers();
 
 Platform.Defaults = getDefaults(PlatformDefaults);
@@ -44,5 +47,6 @@ 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 };
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 201767c3c6..2f19d27a12 100644
--- a/test/browser/modules.test.js
+++ b/test/browser/modules.test.js
@@ -16,6 +16,8 @@ import {
   XHRPolling,
   XHRStreaming,
   WebSocketTransport,
+  FetchRequest,
+  XHRRequest,
 } from '../../build/modules/index.js';
 
 describe('browser/modules', function () {
@@ -60,7 +62,7 @@ describe('browser/modules', function () {
   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');
       });
@@ -68,7 +70,7 @@ 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, Rest, FetchRequest });
         const time = await client.time();
         expect(time).to.be.a('number');
       });
@@ -268,7 +270,7 @@ describe('browser/modules', function () {
       }
 
       for (const clientClassConfig of [
-        { clientClass: BaseRest },
+        { clientClass: BaseRest, additionalModules: { FetchRequest } },
         { clientClass: BaseRealtime, additionalModules: { WebSocketTransport } },
       ]) {
         describe(clientClassConfig.clientClass.name, () => {
@@ -458,4 +460,56 @@ describe('browser/modules', function () {
       }
     });
   });
+
+  describe('HTTP request implementations', () => {
+    describe('without an HTTP request implementation', () => {
+      describe('BaseRest', () => {
+        it('cannot do anything', () => {
+          // TODO
+          // TODO — should it even be constructible?
+        });
+      });
+
+      describe('BaseRealtime', () => {
+        it('is still able to publish messages', async () => {
+          const realtime = new BaseRealtime(ablyClientOptions(), { WebSocketTransport });
+          const channel = realtime.channels.get('channel');
+          await channel.publish();
+        });
+
+        it('throws an error when attempting to use REST functionality', async () => {
+          const realtime = new BaseRealtime(ablyClientOptions(), { Rest, WebSocketTransport });
+
+          let thrownError = null;
+          try {
+            await realtime.time();
+          } catch (error) {
+            expect(error.message).to.equal('no supported HTTP transports available');
+            thrownError = error;
+          }
+
+          expect(thrownError).not.to.be.null;
+          expect(thrownError.message).to.equal('no supported HTTP transports available');
+        });
+      });
+    });
+
+    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;
+      });
+    });
+  });
 });