Firefox 100 Released: A Three-Digit Milestone

What happened

Firefox 100 was released on May 3, 2022, first offered to Release channel users on that date according to the official Mozilla release notes. Mozilla used the milestone to thank the employees, contributors and users who had brought the browser through 17 years and 100 versions, framing the choice to use Firefox as a contribution to a better, open web.

The three-digit version

Reaching version 100 posed a technical challenge: three-digit version numbers had the potential to break sites that parse the browser version, similar to issues seen when browsers first reached version 10. Both the Firefox and Chrome teams ran experiments reporting version 100 in advance and fixed many reported issues, and Firefox 100 shipped alongside Chrome 100, which arrived around the same time.

New features

Firefox 100 added support for displaying captions and subtitles in Picture-in-Picture for YouTube, Prime Video, Netflix and sites using the WebVTT format. It introduced multi-language spell checking, offered a language choice on first run when the browser language did not match the operating system, enabled HDR video on macOS 11+ starting with YouTube, and added hardware-accelerated AV1 video decoding on Windows with supported GPUs.

Web platform

For developers, Firefox 100 landed support for the WritableStream API, giving an interface for writing streaming data to a sink, and added the pipeTo method to ReadableStream to connect a readable stream to a writable one. It also added support for WebAssembly exceptions, allowing C++ exception handling to be expressed in WebAssembly without extra JavaScript helper code and at zero cost to code that does not use exceptions.

Why it mattered

Firefox 100 was as much a symbolic milestone as a feature release, marking 17 years of an independent, open-source browser. The version-number transition it navigated alongside Chrome 100 was a reminder of how deeply browsers are woven into the web, while its media and web-platform additions kept Firefox current.

Related on Skillo

See also: Firefox 115 and the end of Windows 7 support.

Sources

• Firefox 100.0 release notes (Mozilla)

Published date reflects the original event date (2022-05-03). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.