diff --git a/src/api.ts b/src/api.ts
index bfceefe31c..e53dfe2ec7 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -1,9 +1,9 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-import * as chromium from './chromium/api';
-import * as firefox from './firefox/api';
-import * as webkit from './webkit/api';
+import * as chromium from './chromium/crApi';
+import * as firefox from './firefox/ffApi';
+import * as webkit from './webkit/wkApi';
 
 export const Chromium = chromium;
 export const Firefox = firefox;
diff --git a/src/chromium/api.ts b/src/chromium/crApi.ts
similarity index 92%
rename from src/chromium/api.ts
rename to src/chromium/crApi.ts
index d0beab85a8..9607add225 100644
--- a/src/chromium/api.ts
+++ b/src/chromium/crApi.ts
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
+export { BrowserContext } from '../browserContext';
 export { ConsoleMessage } from '../console';
 export { Dialog } from '../dialog';
 export { ElementHandle } from '../dom';
@@ -9,14 +10,15 @@ export { Frame } from '../frames';
 export { Keyboard, Mouse } from '../input';
 export { JSHandle } from '../javascript';
 export { Request, Response } from '../network';
-export { BrowserContext } from '../browserContext';
+export { Page } from '../page';
+
 export { CRSession as CDPSession } from './crConnection';
+export { CRTarget as Target } from './crTarget';
 export { CRAccessibility as Accessibility } from './features/crAccessibility';
 export { CRCoverage as Coverage } from './features/crCoverage';
 export { CRInterception as Interception } from './features/crInterception';
 export { CROverrides as Overrides } from './features/crOverrides';
 export { CRPdf as PDF } from './features/crPdf';
 export { CRPermissions as Permissions } from './features/crPermissions';
-export { Worker, CRWorkers as Workers } from './features/crWorkers';
-export { Page } from '../page';
-export { CRTarget as Target } from './crTarget';
+export { CRWorker as Worker, CRWorkers as Workers } from './features/crWorkers';
+
diff --git a/src/chromium/crBrowser.ts b/src/chromium/crBrowser.ts
index b893442113..2b85c2e59f 100644
--- a/src/chromium/crBrowser.ts
+++ b/src/chromium/crBrowser.ts
@@ -29,9 +29,9 @@ import * as browser from '../browser';
 import * as network from '../network';
 import { CRPermissions } from './features/crPermissions';
 import { CROverrides } from './features/crOverrides';
-import { Worker } from './features/crWorkers';
+import { CRWorker } from './features/crWorkers';
 import { ConnectionTransport } from '../transport';
-import { readProtocolStream } from './protocolHelper';
+import { readProtocolStream } from './crProtocolHelper';
 
 export class CRBrowser extends EventEmitter implements browser.Browser {
   _connection: CRConnection;
@@ -230,7 +230,7 @@ export class CRBrowser extends EventEmitter implements browser.Browser {
     return [...this._targets.values()].find(t => t.type() === 'browser');
   }
 
-  serviceWorker(target: CRTarget): Promise<Worker | null> {
+  serviceWorker(target: CRTarget): Promise<CRWorker | null> {
     return target._worker();
   }
 
diff --git a/src/chromium/crExecutionContext.ts b/src/chromium/crExecutionContext.ts
index 7b329fdb07..cb252e1674 100644
--- a/src/chromium/crExecutionContext.ts
+++ b/src/chromium/crExecutionContext.ts
@@ -17,7 +17,7 @@
 
 import { CRSession } from './crConnection';
 import { helper } from '../helper';
-import { valueFromRemoteObject, getExceptionMessage, releaseObject } from './protocolHelper';
+import { valueFromRemoteObject, getExceptionMessage, releaseObject } from './crProtocolHelper';
 import { Protocol } from './protocol';
 import * as js from '../javascript';
 
diff --git a/src/chromium/crFrameManager.ts b/src/chromium/crFrameManager.ts
index 366f67417d..82cab2f647 100644
--- a/src/chromium/crFrameManager.ts
+++ b/src/chromium/crFrameManager.ts
@@ -25,7 +25,7 @@ import { CRNetworkManager } from './crNetworkManager';
 import { Page } from '../page';
 import { Protocol } from './protocol';
 import { Events } from '../events';
-import { toConsoleMessageLocation, exceptionToError, releaseObject } from './protocolHelper';
+import { toConsoleMessageLocation, exceptionToError, releaseObject } from './crProtocolHelper';
 import * as dialog from '../dialog';
 import { PageDelegate } from '../page';
 import { RawMouseImpl, RawKeyboardImpl } from './crInput';
diff --git a/src/chromium/protocolHelper.ts b/src/chromium/crProtocolHelper.ts
similarity index 100%
rename from src/chromium/protocolHelper.ts
rename to src/chromium/crProtocolHelper.ts
diff --git a/src/chromium/crTarget.ts b/src/chromium/crTarget.ts
index f49b4ece52..4dd91a937d 100644
--- a/src/chromium/crTarget.ts
+++ b/src/chromium/crTarget.ts
@@ -19,7 +19,7 @@ import { CRBrowser } from './crBrowser';
 import { BrowserContext } from '../browserContext';
 import { CRSession, CRSessionEvents } from './crConnection';
 import { Events } from '../events';
-import { Worker } from './features/crWorkers';
+import { CRWorker } from './features/crWorkers';
 import { Page } from '../page';
 import { Protocol } from './protocol';
 import { debugError } from '../helper';
@@ -35,7 +35,7 @@ export class CRTarget {
   private _sessionFactory: () => Promise<CRSession>;
   private _pagePromise: Promise<Page> | null = null;
   private _frameManager: CRFrameManager | null = null;
-  private _workerPromise: Promise<Worker> | null = null;
+  private _workerPromise: Promise<CRWorker> | null = null;
   _initializedPromise: Promise<boolean>;
   _initializedCallback: (value?: unknown) => void;
   _isInitialized: boolean;
@@ -98,13 +98,13 @@ export class CRTarget {
     return this._pagePromise;
   }
 
-  async _worker(): Promise<Worker | null> {
+  async _worker(): Promise<CRWorker | null> {
     if (this._targetInfo.type !== 'service_worker' && this._targetInfo.type !== 'shared_worker')
       return null;
     if (!this._workerPromise) {
       // TODO(einbinder): Make workers send their console logs.
       this._workerPromise = this._sessionFactory()
-          .then(client => new Worker(client, this._targetInfo.url, () => { } /* consoleAPICalled */, () => { } /* exceptionThrown */));
+          .then(client => new CRWorker(client, this._targetInfo.url, () => { } /* consoleAPICalled */, () => { } /* exceptionThrown */));
     }
     return this._workerPromise;
   }
diff --git a/src/chromium/features/crOverrides.ts b/src/chromium/features/crOverrides.ts
index 3cd4a8bb13..887d310787 100644
--- a/src/chromium/features/crOverrides.ts
+++ b/src/chromium/features/crOverrides.ts
@@ -17,7 +17,7 @@
 
 import { BrowserContext } from '../../browserContext';
 import { CRFrameManager } from '../crFrameManager';
-import { Page } from '../api';
+import { Page } from '../crApi';
 
 export class CROverrides {
   private _context: BrowserContext;
diff --git a/src/chromium/features/crPdf.ts b/src/chromium/features/crPdf.ts
index 59607cf9d3..c5bb273c64 100644
--- a/src/chromium/features/crPdf.ts
+++ b/src/chromium/features/crPdf.ts
@@ -17,7 +17,7 @@
 
 import { assert, helper } from '../../helper';
 import { CRSession } from '../crConnection';
-import { readProtocolStream } from '../protocolHelper';
+import { readProtocolStream } from '../crProtocolHelper';
 
 type PDFOptions = {
   scale?: number,
diff --git a/src/chromium/features/crWorkers.ts b/src/chromium/features/crWorkers.ts
index f7650509db..3ec0af6134 100644
--- a/src/chromium/features/crWorkers.ts
+++ b/src/chromium/features/crWorkers.ts
@@ -24,13 +24,13 @@ import * as types from '../../types';
 import * as js from '../../javascript';
 import * as console from '../../console';
 import { CRExecutionContext } from '../crExecutionContext';
-import { toConsoleMessageLocation, exceptionToError } from '../protocolHelper';
+import { toConsoleMessageLocation, exceptionToError } from '../crProtocolHelper';
 
 type AddToConsoleCallback = (type: string, args: js.JSHandle[], location: console.ConsoleMessageLocation) => void;
 type HandleExceptionCallback = (error: Error) => void;
 
 export class CRWorkers extends EventEmitter {
-  private _workers = new Map<string, Worker>();
+  private _workers = new Map<string, CRWorker>();
 
   constructor(client: CRSession, addToConsole: AddToConsoleCallback, handleException: HandleExceptionCallback) {
     super();
@@ -39,7 +39,7 @@ export class CRWorkers extends EventEmitter {
       if (event.targetInfo.type !== 'worker')
         return;
       const session = CRConnection.fromSession(client).session(event.sessionId);
-      const worker = new Worker(session, event.targetInfo.url, addToConsole, handleException);
+      const worker = new CRWorker(session, event.targetInfo.url, addToConsole, handleException);
       this._workers.set(event.sessionId, worker);
       this.emit(Events.Workers.WorkerCreated, worker);
     });
@@ -52,12 +52,12 @@ export class CRWorkers extends EventEmitter {
     });
   }
 
-  list(): Worker[] {
+  list(): CRWorker[] {
     return Array.from(this._workers.values());
   }
 }
 
-export class Worker extends EventEmitter {
+export class CRWorker extends EventEmitter {
   private _client: CRSession;
   private _url: string;
   private _executionContextPromise: Promise<js.ExecutionContext>;
diff --git a/src/firefox/api.ts b/src/firefox/ffApi.ts
similarity index 99%
rename from src/firefox/api.ts
rename to src/firefox/ffApi.ts
index e2791c2aa5..3f24f13b16 100644
--- a/src/firefox/api.ts
+++ b/src/firefox/ffApi.ts
@@ -1,16 +1,18 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-export { TimeoutError } from '../errors';
-export { Keyboard, Mouse } from '../input';
 export { BrowserContext } from '../browserContext';
+export { ConsoleMessage } from '../console';
 export { Dialog } from '../dialog';
-export { JSHandle } from '../javascript';
 export { ElementHandle } from '../dom';
+export { TimeoutError } from '../errors';
+export { Frame } from '../frames';
+export { Keyboard, Mouse } from '../input';
+export { JSHandle } from '../javascript';
+export { Request, Response } from '../network';
+export { Page } from '../page';
+
 export { FFAccessibility as Accessibility } from './features/ffAccessibility';
 export { FFInterception as Interception } from './features/ffInterception';
 export { FFPermissions as Permissions } from './features/ffPermissions';
-export { Frame } from '../frames';
-export { Request, Response } from '../network';
-export { Page } from '../page';
-export { ConsoleMessage } from '../console';
+
diff --git a/src/webkit/api.ts b/src/webkit/wkApi.ts
similarity index 90%
rename from src/webkit/api.ts
rename to src/webkit/wkApi.ts
index bd18c96726..e0f61d4b97 100644
--- a/src/webkit/api.ts
+++ b/src/webkit/wkApi.ts
@@ -1,13 +1,14 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-export { TimeoutError } from '../errors';
 export { BrowserContext } from '../browserContext';
-export { JSHandle } from '../javascript';
+export { ConsoleMessage } from '../console';
+export { Dialog } from '../dialog';
 export { ElementHandle } from '../dom';
+export { TimeoutError } from '../errors';
 export { Frame } from '../frames';
-export { Mouse, Keyboard } from '../input';
+export { Keyboard, Mouse } from '../input';
+export { JSHandle } from '../javascript';
 export { Request, Response } from '../network';
 export { Page } from '../page';
-export { Dialog } from '../dialog';
-export { ConsoleMessage } from '../console';
+
diff --git a/src/webkit/wkExecutionContext.ts b/src/webkit/wkExecutionContext.ts
index 74462359b4..678eae53c0 100644
--- a/src/webkit/wkExecutionContext.ts
+++ b/src/webkit/wkExecutionContext.ts
@@ -17,7 +17,7 @@
 
 import { WKTargetSession, isSwappedOutError } from './wkConnection';
 import { helper } from '../helper';
-import { valueFromRemoteObject, releaseObject } from './protocolHelper';
+import { valueFromRemoteObject, releaseObject } from './wkProtocolHelper';
 import { Protocol } from './protocol';
 import * as js from '../javascript';
 
@@ -144,7 +144,7 @@ export class WKExecutionContext implements js.ExecutionContextDelegate {
       return valueFromRemoteObject(response.result);
     }).catch(rewriteError);
 
-    function unserializableToString(arg) {
+    function unserializableToString(arg: any) {
       if (Object.is(arg, -0))
         return '-0';
       if (Object.is(arg, Infinity))
@@ -161,7 +161,7 @@ export class WKExecutionContext implements js.ExecutionContextDelegate {
       throw new Error('Unsupported value: ' + arg + ' (' + (typeof arg) + ')');
     }
 
-    function isUnserializable(arg) {
+    function isUnserializable(arg: any) {
       if (typeof arg === 'bigint')
         return true;
       if (Object.is(arg, -0))
@@ -180,11 +180,7 @@ export class WKExecutionContext implements js.ExecutionContextDelegate {
       return false;
     }
 
-    /**
-     * @param {!Error} error
-     * @return {!Protocol.Runtime.evaluateReturnValue}
-     */
-    function rewriteError(error) {
+    function rewriteError(error: Error): Protocol.Runtime.evaluateReturnValue {
       if (error.message.includes('Object couldn\'t be returned by value'))
         return {result: {type: 'undefined'}};
 
diff --git a/src/webkit/protocolHelper.ts b/src/webkit/wkProtocolHelper.ts
similarity index 100%
rename from src/webkit/protocolHelper.ts
rename to src/webkit/wkProtocolHelper.ts