Introducing WebKit Build Archives

WebKit contributors have long relied on the WebKit Nightly builds. The WebKit project has been posting these builds since r11994, January 11, 2006. Since their introduction, the nightlies have served a meaningful purpose: “Use the newest untested code in WebKit to find bugs, verify fixes and try the latest features.”

Today we’re excited to roll out some improvements to how we deliver WebKit builds. Building upon the continuous integration infrastructure from, we are now making every successful build of WebKit available! This is a significant improvement from the existing nightly infrastructure, as it should effectively allow bisection down to a single commit.

With these enhancements, WebKit Build Archives will replace WebKit Nightly builds. The new build archives are intended for engineers that contribute to WebKit development to test and diagnose issues. These builds do not have a signed app launcher nor an auto-update system, making them ill-suited as a daily web browsing application. To regularly try out recent WebKit builds on macOS, we recommend downloading and installing Safari Technology Preview, a quality-checked release that automatically updates every two weeks.


Starting with r219240, built products are being stored at a publicly accessible location. These builds can be accessed via the OpenSource/Tools/Scripts/bisect-builds tool. This script will allow anyone to perform a simple bisection over the range of available WebKit builds.

For those without WebKit source checkouts, minified release archives can be downloaded directly from the WebKit Build Archives page. These archives contain a README file with usage instructions.

Platform Support

Currently, archives for the following platforms are available: macOS El Capitan, macOS Sierra, and macOS High Sierra.

Archive Types

Two types of archives are stored: full product, and minified product. Full product archives are exactly what comes out of the build pipeline. These builds are currently used by our CI infrastructure for testing WebKit. Because these builds contain dSYM files (on macOS) they are quite large, and would be undesirable for bisecting. To mitigate the size issue, minified archives are also produced. These minified archives contain only what is necessary to function, and are roughly 10x smaller than the full product archives. This makes them quick to download and extract, ideal for fast bisection and testing.

Archive Retention

Full product archives will be retained for 14 days, while minified archives will expire after 2.5 years.


The development of the bisect-builds script is just beginning, and we welcome any help to improve it. Please file bugs at if you run into any issues or have enhancement requests. Or better yet, feel free to contribute a patch to help improve the experience!