Almost exactly one year ago we launched WebContainers, our in-browser operating system capable of running full Node.js toolchains. The ability to instantly build the web using the web struck a chord with developers, and millions of developers now use StackBlitz every month for instant bug reports, live documentation examples, and much more.

While WebContainers are built entirely on web standardized APIs like WebAssembly and Service Workers, to date they've been limited to running in Chromium-based browsers due to differences in how these APIs work across different browser implementations. This can be worked around to some degree in userland, but because WebContainers are amongst the most sophisticated applications that run inside browser engines, we needed to team up with platform vendors directly to bring these instant development experiences to all browsers and devices.

Since joining the Bytecode Alliance a few months back, we’ve been collaborating with the Mozilla team on bridging this gap. Today we’re excited to share the amazing news:

🎉 WebContainers are now supported in Firefox, desktop and mobile! 🎉

You can try the public beta now in your Firefox browser on your desktop or mobile device by going to and starting a new project:

Start building & debugging web applications instantly in Firefox on

What does it mean for the web ecosystem? Permalink

This is a major milestone for web developers using Firefox, as you can now:

This is also a major milestone for the Web, as running entire development environments is one of the key stress tests of any platform. Crucial to note, we are talking here about web standardized APIs and not proprietary technology.

This remarkable achievement brings us closer to a vision both Mozilla and StackBlitz share:

It should be as easy to build the web as it is to browse it.

Web standards are important. They ensure that progress in one area unlocks new possibilities for the whole ecosystem. In this case, we are making it easier to build the web. But why?

We see three main reasons for why it’s so crucial to bring web development in-browser:

  1. Setting up a new developer environment is, sadly, a long and frustrating all-too-common experience - it’s time-consuming, ridden with bugs, unclear errors, and increasingly insecure. We are eliminating it.
  2. The introduction of browser DevTools was met with great enthusiasm because finally, developers could debug their applications inside their browser. Why stop there? Imagine having the entire IDE inside the browser where you can both develop the web, test it, and debug it, all in one window. Not being able to do so is a bug, not a feature, and we are changing that.
  3. Web development should be accessible to people without deep dev expertise. Just as our friends at Mozilla say, the increasing complexity of web development "disempowers site authors by hampering their ability to express themselves." We are making writing applications no-code or low-code even easier.

We are really excited about the future that this milestone unlocks, and we hope you are too.

Try the public alpha now in your Firefox browser (on your desktop or a mobile device) by going to and starting a new project. Or, if you already are a Vite fan, simply visit

Share your feedback with us! We are looking forward to building the future of web with you.

PS - Interested in the deep technical details on how we made this happen? Stay tuned for the blog post from our engineering team later this week.

Eric Simons

CEO at StackBlitz making web development fast & secure. Viva la Web!

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