Mozilla Developers

Developer tools, resources, videos and more

Firefox Quantum: Developer Edition

Get the latest features, fast performance, and the development tools you need to build for the open web.

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Developer resources

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

Fresh from our blog

  • View Source 5 comes to Amsterdam

    Mozilla’s View Source Conference is back! This year we’re in Amsterdam, September 30 – October 1, 2019. Tickets are available now. We’ve shifted our focus to take a deeper look at the web platform and how it is evolving and to offer attendees access to the folks who are shaping today’s web and the web of the future.

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  • CSS Scroll Snap Updated in Firefox 68

    The CSS Scroll Snap specification gives us a way in CSS to snap between different elements in a page or scrolling component. In this post, Rachel Andrew explains how scroll snapping works, why we had a situation where browsers were running different versions of the specification, and how that’s changing.

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  • CSS Grid Level 2 – subgrid is coming to Firefox

    The subgrid feature which is part of Level 2 of the CSS Grid Specification is not yet shipping in any browser, but is now available for testing in Firefox Nightly. This is a feature that, if you have used CSS Grid for a layout of any complexity, you are likely to be pretty excited about

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Projects we love

A new layout system for the Web.

See grids in action

Mozilla’s next-generation web engine.

Get involved

A systems programming language that is fast and safe.

Check out Rust

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

Learn more

Build exciting virtual reality Web pages using HTML.

Start building