Online Firefox Browser Testing

Browserling offers free online cross-browser testing in the Mozilla Firefox browser. Say goodbye to your browser testing lab and virtual machines – we have installed Mozilla Firefox on our cloud servers and we stream the browser to you. You don't even need to install any additional software as Browserling is powered by HTML5 and JavaScript. The Firefox browser runs on real computers and it's not a fake browser simulator or emulator.

We install the latest Firefox versions as soon as they get released. At the moment, we have all Firefox versions starting from Firefox 1 to Firefox 132 (currently the latest version). Mozilla has a rapid release cycle and new Firefox versions get released every 4 weeks. We monitor the Firefox release servers and as soon as we see a new release, we install it on our cross-browser testing platform.

Try Online Firefox Now!

Please use the widget below to load an online Firefox. First, enter a website address and then click the test button. You'll instantly get connected to a virtual machine that runs Firefox 125:

The free version lets you use the latest Firefox version for three minutes, but to get unlimited access, you'll have to buy the developer plan.

Online Mozilla Firefox Testing FAQ

Can I use Firefox online without downloading it?

Yes! If you want to use online Firefox without downloading or installing anything, you can try it right here in your browser through our online Firefox testing platform. Simply open this link to start browsing: browserling.com/browse/firefox.

Can I test my website on Firefox without a Windows computer?

Yes! You don't need a Windows computer to test your site on Firefox. You can use Browserling to run Firefox online from any device, whether you're on a Mac, Linux, Chromebook, or even a tablet. Click here to load a Firefox browser.

Do you run emulated Firefox?

No, we don't run Firefox emulators or Firefox simulators. We've installed Firefox on a real computer and we run native Firefox.

When did Firefox hit version 100?

Firefox released version 100 on May 3, 2022. It took Mozilla 17 years to go from version 1 to version 100. If you'd like to try this anniversary version online, then we have it installed in our browser cloud and you can access it via this quick browsing URL: browserling.com/browse/firefox/100.

Which browser reached version 100 first – Firefox or Chrome?

In our blog post, we predicted that Chrome will reach version 100 first and we were right. Even though Firefox was always ahead of Chrome by a couple of versions, Chrome accelerated in the final stretch and reached version 100 first on March 29, 2022. It's because Chrome switched from a six week release cycle to a four week release cycle, while Firefox didn't change its release schedule. If you'd like, you can also try online Chrome version 100 via our quick browsing URL: browserling.com/browse/chrome/100.

Can I test my website on old versions of Firefox?

Yes! We have every major version of Firefox installed, starting from version 1. If you need to check how your site looks on an older version, you can load any Firefox version through our quick browser access link. For example, to open Firefox 50, visit: browserling.com/browse/firefox/50, and to open Firefox 57 (codename Quantum), visit browserling.com/browse/firefox/57.

How can I try the very first version of Firefox?

We have installed all Firefox versions starting from version 1 and you can try the very first version of Firefox online via our quick browsing URL: browserling.com/browse/firefox/1.

When will the next Firefox version be released?

Currently, the latest version is Firefox 132. The next version will be Firefox 133 and it will be released later this February. We'll be installing this version as soon as it's released and write a blog post about it as well.

What is Firefox Quantum?

Firefox Quantum was a major update to Firefox released in 2017. It made the browser faster, more efficient, and better at using multiple CPU cores. Mozilla completely rebuilt Firefox's engine, making web pages load quicker while using less memory. It also introduced a cleaner design and better security. If you want to try Firefox Quantum, you can access it online via our platform at browserling.com/browse/firefox/57.

Does Firefox support headless testing?

Yes! Firefox 56 added a headless mode that can be launched via -headless argument. You can't yet run the headless Firefox on Browserling, but we're working on a new product called Headless API that will let you launch headless Firefox and run your JavaScript tests and automate various actions. Stay tuned!

Why is cross-browser testing in Firefox important?

Firefox is the third most popular browser (after Chrome and Safari). As a lot of people love Firefox, you have to make sure that the websites and JavaScript code that you write work correctly in Firefox.

Why does my website look different in Firefox compared to Chrome?

Each browser renders websites a little differently because they use different rendering engines. Firefox uses Gecko, while Chrome uses Blink. If your site looks off in Firefox, check for CSS or JavaScript issues in Firefox Developer Tools (Ctrl+Shift+I on Windows/Linux, Command+Opt+I on Mac).

Why does my JavaScript work in Chrome but not in Firefox?

Browsers interpret JavaScript slightly differently. Firefox uses the SpiderMonkey engine, while Chrome uses V8. Some JavaScript features might work in one but not the other. Check the console in Firefox Developer Tools (press F12 or Ctrl+Shift+I) for errors.

Can I set Firefox as my default browser?

Absolutely! On Windows, go to Settings - Apps - Default Apps and choose Firefox under "Web browser." On Mac, open System Settings - Desktop & Dock - Default web browser. This way, all links will open in Firefox by default.

Can I access Firefox Developer Tools from Browserling?

Yes, of course! You can open the Firefox Developer Tools from the menu by selecting Tools, then Web Developer, then Toggle Tools or use the keyboard shortcut Ctrl+Shift+I on Windows and Linux and the keyboard shortcut Command+Option+I on macOS.

What's the best way to debug JavaScript issues in Firefox?

Firefox Developer Tools! You can access them via Ctrl+Shift+I (Windows/Linux) or Command+Opt+I (Mac). It includes an inspector, console, debugger, and network tools to help you find and fix issues.

Does Firefox block certain websites or scripts?

Yes, Firefox has built-in tracking protection that can block some scripts, ads, and cookies. If a site isn't working as expected, try disabling Enhanced Tracking Protection (ETP) or running it in a private window.

Does Firefox have better privacy than other browsers?

Yes! Firefox is known for its strong privacy protections. It blocks third-party trackers, fingerprinting, and cryptominers by default. If privacy is a priority, Firefox is a great choice.

Can I use Firefox without logging into a Mozilla account?

Yes! Firefox works without requiring an account. However, if you want to sync bookmarks, history, and passwords across devices, you'll need to sign in to a Mozilla account.

Can I use Firefox without installing add-ons or extensions?

Yes! Firefox works perfectly fine without any add-ons by default. But if you want extra features like ad-blocking, dark mode, or privacy tools, you can install extensions from the Firefox Add-ons store. Keep in mind that too many add-ons might slow things down.

How do I clear cookies and cache in Firefox for testing?

If you want to delete the saved cookies, go to Firefox settings, then "Privacy & Security" and click "Clear Data". You can also press Ctrl+Shift+Del (on Windows/Linux) or Command+Shift+Del (on macOS) to open the "Clear History" menu instantly.

Does Firefox support WebP images and AVIF?

Yes! Firefox supports both WebP and AVIF image formats, which are more efficient than PNG or JPEG. If an image isn't loading, make sure you've updated Firefox and aren't using an old version.

Does Firefox support CSS Grid and Flexbox?

Yes! Firefox has excellent support for modern CSS features like Grid and Flexbox. Plus, it has a Grid Inspector and Flexbox Debugger built into Developer Tools. Just open DevTools and check the Layout tab to see how elements are positioned.

Why is Firefox using so much memory (RAM)?

Firefox uses multiple processes to keep things running smoothly, but sometimes it can take up a lot of memory. Try closing unused tabs, disabling heavy extensions, or enabling "Memory Saver" in settings. You can also check about:performance to see what's using the most resources.

What is a Firefox emulator?

A Firefox emulator is a program that tries to copy how Firefox works without actually running the real browser. It can show how websites might look in Firefox, but it's not accurate because it doesn't use Firefox's actual rendering engine. For the best results, it's better to use a real Firefox browser, like the one we're offering.

What is a Firefox simulator?

A Firefox simulator is a tool that mimics Firefox's appearance and behavior without using its actual rendering engine. While it can help with quick previews, it can't fully replicate how Firefox processes web pages. For precise results, testing in the real Firefox browser is recommended.

Can I automate Firefox testing?

If you want to run automated tests without setting up anything, stay tuned for our upcoming Headless API, which will let you run scripts in online Firefox through curl, wget, or cloud test runner.

Can you help us write a Firefox extension or solve a Firefox code issue?

We're always ready to help! We have been solving cross-browser testing problems for over 10 years and have all the Firefox versions installed (from version 1 – going back to 2004 to version 132 – released last month). We know every change that's happened in Firefox over the years. Please contact us at hello@browserling.com and we'll help you with your Firefox problem.

What's the difference between Live API and Headless API?

Our Live API technology lets you embed a live and interactive online Firefox browser in your own application or web page via an iframe. It has a neat JavaScript API for doing that. The Headless API on the other hand lets you automate an online Firefox browser without seeing it. We're still working on Headless API and will be releasing it soon!

Support

For any additional questions about cross-browser testing in Firefox please contact us at support@browserling.com or use our contact form.