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 come out. At the moment, we have all Firefox versions starting from Firefox 3 to Firefox 88 (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 version released, we install it on our cross-browser testing platform.

Try Firefox in Browserling 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 88:

The free version lets you use Firefox 88 (the latest version) for three minutes but to get unlimited access, you'll have to buy the developer plan.

Mozilla Firefox Testing FAQ

When will Firefox hit version 100?

Firefox is on a rapid four to five-week release cycle and at the moment the latest version is Firefox 88. That means in about 48 to 60 weeks Firefox will reach version 100, which is approximately February 2022.

Who will reach version 100 first – Firefox or Chrome?

At the moment, Google Chrome is at version 90 and Mozilla Firefox is at version 88. That means Chrome is 2 versions ahead of Firefox. However, Google Chrome is on a little bit slower release cycle than Firefox, averaging a new version every six weeks. As Firefox has a quicker release cycle, it's expected to hit version 100 first in February 2022, while Chrome is expected to hit version 100 only in June or July of 2022.

When will the next Firefox version be released?

Currently, the latest version is Firefox 88. The next version will be Firefox 89 and it will be released on June 1, 2021. We'll be installing this version as soon as it's released and making a blog post about it as well.

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 works correctly in Firefox.

Do you run emulated Firefox?

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

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.

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 3 - going back to 2008 to version 88 - released just a week ago). We know every change that's happened in Firefox over the years. Please contact us at 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 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 the Firefox browser without seeing it. We're still working on Headless API and will be releasing it soon.


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