How do I check cross browser compatibility of my website?

Start from your analytics: list the browsers, versions, and devices your visitors use, plus the oldest versions you still support. Open the site in each one, on a cloud browser farm or in virtual browsers with nothing to install, and walk your key flows, such as sign-up, search, and checkout, checking layout, fonts, forms, and the browser console for errors. Then automate those flows with Selenium, Playwright, or Cypress so every release runs across the same browser list. Our complete guide to cross browser testing shows how to build that list.

What are the most common cross browser compatibility issues?

The five most common are layout shifts, unsupported CSS, inconsistent JavaScript APIs, browser-styled form elements, and font rendering differences. CSS renders differently across Blink, WebKit, and Gecko. See the full guide on cross browser compatibility.

What do I get with TestMu AI cross browser testing?

3,000+ browser-OS combinations, with DevTools, geolocation across 170+ countries, network throttling, and bug logging to 65+ trackers in every session. The free plan has limited monthly minutes and needs no credit card. Unlimited live testing is $15/month, billed annually.

How much does cross browser testing cost?

TestMu AI is free for life on limited monthly minutes, with no credit card. Unlimited live testing starts at $15/month, billed annually. See pricing for every plan.

What is the difference between cross browser testing and responsive testing?

Responsive testing checks how your layout adapts to different screen sizes; cross browser testing checks how different rendering engines interpret the same code. A site can be perfectly responsive in Chrome and still break in Safari, so you need both.

What is the difference between cross browser testing and cross platform testing?

Cross browser testing checks your site across browsers and their versions, such as Chrome, Safari, Firefox, and Edge. Cross platform testing checks it across operating systems and devices, such as Windows, macOS, iOS, and Android. The two overlap: Safari behaves differently on macOS and iOS.

Can cross browser testing be fully automated?

Yes. Functional flows, visual regression, and compatibility checks run automatically on every commit using Selenium, Playwright, or Cypress, and KaneAI writes tests from plain English. Most teams keep a small manual layer for exploratory checks.

How do I run cross browser tests with Playwright?

Define a project for Chromium, Firefox, and WebKit in playwright.config, then run them in parallel. For branded Chrome and Edge, older versions, and Windows and macOS machines, point Playwright at the TestMu AI grid by updating the connection endpoint. Existing specs run unchanged. Playwright drives WebKit rather than branded Safari, so check Safari itself in a live session or a Selenium run on macOS.

Can I run the Safari browser on Windows?

Not natively. Apple discontinued Safari for Windows in 2012. TestMu AI streams Safari from a macOS VM to your Windows browser, so you can test current and legacy Safari versions without a Mac. See Safari browser for Windows, or the Windows emulator online.

How do I test a website on mobile browsers?

Open your URL on an Android emulator or iOS simulator instead of resizing a desktop window. TestMu AI runs Chrome, Safari, and Firefox on virtual Android and iOS devices, with swipe, zoom, and rotate controls, Chrome DevTools, and Safari Web Inspector. For tests that need physical hardware, use Real Device Cloud.

What is online browser testing?

Online browser testing runs your site in browsers hosted in the cloud and streamed to your machine, with nothing installed locally. TestMu AI offers 3,000+ browser-OS combinations, so there is no VM or device lab to maintain.

How do I test a browser online without installing it?

Open a cloud session instead of an install. Sign in, choose the browser and OS, enter your URL, and TestMu AI streams a live session into the tab you are already in. Native DevTools are included in every session. That cloud session is a remote browser.

Is web based browser testing as reliable as a local browser install?

Yes for desktop browsers. TestMu AI runs real browser builds on Windows and macOS VMs, so rendering, JavaScript behaviour, and font handling match a local install. Mobile sessions run on Android emulators and iOS simulators, which suit layout and rendering checks.

Can AI agents run browser sessions in the cloud?

Yes. TestMu AI Browser Cloud is browser infrastructure for AI agents. It provides real, full-featured Chrome sessions on demand, a built-in tunnel so agents can reach localhost and staging, persistent browser state, and full session transparency for debugging. It stays agent agnostic, so Claude, Cursor, Gemini, OpenAI Computer Use, and custom agents can drive it.

Cross Browser Testing on 3,000+ Real Desktop and Mobile Browsers

Open a live Chrome, Firefox, Edge, or Safari on macOS session in seconds with TestMu AI, a cross browser testing tool with 3,000+ browser-OS combinations.

Start free with Google

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Trusted by 3M+ users globally at

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More browsers in testing. Fewer bugs in production.

Check rendering across browsers and versions: desktop browsers on Windows and macOS, mobile browsers on Android emulators and iOS simulators.

Start free with Google

Debug live in any browser

Click, scroll, and reproduce issues live on real desktop browsers, Android emulators, and iOS simulators.

Start a live browser session free

Test on Chrome, Firefox, Edge, Opera, Brave and DuckDuckGo on Windows and macOS, and Safari on macOS, including latest and legacy versions.

Android emulators and iOS simulators running Chrome, Safari, and Firefox. Swipe, zoom, and rotate the device.

Open Chrome DevTools, Firefox DevTools, or Safari Web Inspector inside the session. No tool-switching, no lost context.

Browser picker with Chrome versions and screen resolutions for a live cross browser testing session

Online browser testing, no local setup

Every session runs on a cloud VM or emulator and streams into the tab you already have open.

Start an online browser test

Pick a browser and OS, enter your URL, and click Start to catch cross browser issues. Nothing to download or install.

TestMu AI keeps every browser, OS image up to date, and wipes each VM when your session ends.

Turn on the secure tunnel to run cross browser tests on local or staging builds before they reach a public URL.

Chrome, Safari, and Firefox streamed to desktop, tablet, and phone screens from the cloud

Run browser automation with natural language

Describe what to test in plain English to KaneAI - end to end QA testing agent. It writes and runs the test.

Run browser automation with KaneAI

Describe the flow in plain English, or hand KaneAI a PRD, Jira ticket, or screen recording. It plans the steps and assertions.

KaneAI finds elements by intent and re-anchors steps when your UI shifts. When a run fails, it explains why and drafts the bug ticket.

Take generated tests into your existing codebase, or run them in parallel across browsers with HyperExecute - 70% faster test execution.

KaneAI authoring steps turning plain-English instructions into an automated test

What Is Cross Browser Testing?

Cross browser testing is how you confirm a website behaves the same for every visitor, whatever browser, browser version, operating system, or screen size they use. Chrome and Edge render pages with the Blink engine, Safari with WebKit, and Firefox with Gecko, so the same HTML, CSS, and JavaScript can lay out, animate, or fail differently in each one.

A cross browser test catches the bugs a single-browser check misses: a flexbox gap that collapses in an older Safari, a date input that falls back to a plain text field, a web font that renders differently on Windows and macOS, or a JavaScript API one engine has not shipped yet. Teams test by hand in live sessions to explore a release or reproduce a customer report, and run automated Selenium, Playwright, or Cypress suites on every commit to catch regressions.

On TestMu AI, desktop sessions run real browser builds on Windows and macOS cloud machines, across 3,000+ browser and OS combinations. Safari runs as Apple's own browser on macOS, so a Safari-only bug shows up the way your Mac users see it. A WebKit build on Linux or Windows, such as the one Playwright ships, is close to Safari but is a different browser. Mobile browser sessions run on Android emulators and iOS simulators, which suit layout and rendering checks. When a test needs physical hardware, such as touch response, the camera, or biometrics, run it on Real Device Cloud, with 50,000+ real devices.

Most teams start with the browsers in their analytics, add the oldest versions they still support, and automate the flows that bring in revenue, such as sign-up, search, and checkout. Our cross browser testing guide shows how to build that browser matrix, when to test manually and when to automate, and a checklist to run before each release.

How to Run a Cross Browser Test on TestMu AI

A live session needs no install: pick the browser, open your page, debug it, and send the bug to your tracker.

Step 1
Pick a Browser and OS
Open Real Time in the dashboard, choose desktop or mobile, then pick the browser, version, operating system, and screen resolution.
Step 2
Open Your URL or Localhost
Enter a public URL, or turn on the LT Tunnel or the Underpass app to test a localhost or staging build behind your firewall.
Step 3
Debug in the Live Session
Click through the page with Chrome DevTools or Safari Web Inspector open, and switch on network throttling or geolocation when the bug depends on them.
Step 4
Log the Bug or Automate It
Mark as Bug sends an annotated screenshot to Jira, Azure DevOps, or GitHub Issues with the browser, OS, and URL attached. Then run the same flow as a Selenium, Playwright, or Cypress test in parallel.

Start a live cross browser test

What does browser compatibility testing cover?

Browser compatibility testing covers browsers and their versions, operating systems, screen sizes, networks, and locations. A TestMu AI live session lets you test each one. For why rendering engines differ, read our guide to cross browser compatibility.

Pick from the screen resolutions offered for each browser and OS to check your responsive breakpoints without resizing a window.

Throttle the session to Slow 3G, Fast 3G, 4G, 5G, or offline, or set a custom speed and latency.

Route the session through an IP in any of 170+ countries to check localized content, currency, language, and regional privacy banners.

Upload txt, pdf, doc, xls, docx, and xlsx files, or files from Google Drive, to test upload flows in a desktop browser session.

Turn on NVDA in a Windows session or VoiceOver in a macOS session to check keyboard navigation, focus order, and spoken output.

Try all 5 features free

Browser, version, and screen resolution picker for a live desktop session

Get started with your first cross browser test

Cross browser testing guide

Walkthrough on performing cross browser testing with TestMu AI, plus a comparison of the best cross browser testing tools for 2026.

Read the guide

Live interactive browser testing

Start a live cross browser session on desktop browsers, Android emulators, or iOS simulators.

Test on desktop browsers

Test on mobile browsers

Automated browser testing

Run automated Selenium, Playwright, and Cypress suites in parallel on the cross browser testing cloud.

View documentation

More browser coverage. Zero maintenance overhead.

No infrastructure to manage

Anyone on the team opens a session from the dashboard, with no machines, emulators, or browser versions to maintain.

Isolated, encrypted sessions

Each session runs in its own VM or emulator, encrypted in transit and at rest. SOC 2 Type II and ISO 27001 certified.

Starts at $15/month

Free for life on limited monthly minutes, no credit card. Unlimited live testing from $15/month, billed annually.

Run your first cross browser test

Test on 3,000+ browser-OS combinations

Browser versions and rendering engines covered by TestMu AI cross browser testing
Cross Browser Testing	Versions	Engine
Test on Chrome Browsers	37 to the latest stable, plus Beta	Blink
Test on Safari Browsers	5.1 to 18, plus 26 and 27	WebKit
Test on Firefox Browsers	32 to the latest stable, plus Beta	Gecko
Test on Edge Browsers	79 to the latest stable, plus Beta, and legacy Edge 15 to 18	Blink (EdgeHTML for 15 to 18)
Test on Opera Browsers	23 to 110	Blink
Test on Brave Browsers	1.34 to 1.64	Blink

See the full list of browsers. For biometrics, camera, or on-device performance checks, step up to Real Device Cloud - 50,000+ real devices.

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