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Firefox DevTools

Modern tools for Web development.

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MDN

The best resource for the Open Web.

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Firefox DevTools

Edit and debug HTML, CSS, and JavaScript.

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WebAssembly

Use the .wasm format as a compiler target.

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Cross-browser testing

Easily test your site on every browser and operating system.

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Events to check out

Fresh from our blog

  • Building the DOM faster: speculative parsing, async, defer and preload

    In 2017, the toolbox for making sure your web page loads fast includes everything from minification and asset optimization to caching, CDNs, code splitting and tree shaking. Understanding what goes on inside a browser is still the most powerful tool for every web developer. This article breaks down how defer and async work and how you can leverage the new keyword preload.

    Read more

  • Meta 2 AR Headset with Firefox

    One of the biggest challenges in developing immersive WebVR experiences today is that immersion takes you away from your developer tools. With Meta’s new augmented reality headset, you can work on and experience WebVR content today without ever taking a headset on or off, or connecting developer tools to a remote device.

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Projects we love

A new layout system for the Web.

See grids in action

Mozilla’s next-generation web engine.

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A systems programming language that is fast and safe.

Check out Rust

Powerful Web technologies that help push games to the new level.

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Build exciting virtual reality Web pages using HTML.

Start building