A GNU IceCat fork · continuing Firefox's free line

Free software Firefox.
Built on a clock.

Cryolite is a hardened GNU IceCat fork — Firefox ESR with the GNU freedom layer, rebuilt by a fully scripted pipeline: a clean source tree, a pinned ESR tag, a scripted rebrand, a patch layer, an optimized build, a smoke gate — every six weeks, without fail. ESR security advisories are watched weekly in between. The Chromium side of the family is Fluorite; this is its Gecko twin.

Get Cryolite The IceCat story
140.9.1-gnu1Current base tag
42 daysRelease cycle
7×/weekSecurity watch
100%Scripted pipeline
Next scheduled cycle release
—
42-day cadence from last promotion · ESR security respins land any time they're needed

What makes it different

ESR stability, frozen in ice

Cryolite rides the Firefox Extended Support Release: the branch Mozilla itself considers stable enough for enterprises. Fewer surprises, longer support windows, security fixes without churn.

The GNU freedom layer

Inherited from IceCat: only free software licenses for built-in extensions, LibreJS to detect non-free JavaScript, and trademark-safe rebranding. Your browser respects you and the four freedoms.

Scripted rebrand, reviewable patches

The mechanical IceCat→Cryolite pass is one audited script, exactly like upstream's own makeicecat. Everything else lives as discrete patches in a reviewable layer.

Release-optimized builds

Official-build configuration: optimizations on, debug symbols trimmed, updater and crash reporter off. What ships is a browser, not a development snapshot.

Smoke gate before promote

Every build must introduce itself (--version) and render a page headlessly before it earns a place in the dist tree. Binaries only land once they've proven themselves.

Clean-tree discipline

Profiles live outside the build tree entirely. Each cycle starts from zero: every artifact traces back to exactly one ESR tag and one patch set.

All features in detail →

Where it comes from

Cryolite didn't appear out of nowhere. It stands on decades of browser work:

  • Firefox ESR — Mozilla's extended-support branch: the stable, security-maintained core that powers Thunderbird, Tor Browser and half the enterprise world.
  • GNU IceCat — the FSF's free-software Firefox, produced by the makeicecat pipeline since 2008: free licenses only, LibreJS, privacy defaults, no trademark strings.
  • Cryolite — a direct fork of IceCat, continuing that living codebase with a security/stability-first mindset: fresh tree, pinned ESR tag, scripted rebrand, tested artifacts, weekly security tracking.

Read the full lineage

The pipeline

  1. PinResolve the newest vX.Y.Z-gnuN tag from the gnuzilla repository and pin the cycle to it.
  2. TransformRun makeicecat: Firefox ESR sourceball, GPG-verified, GNU patches and freedom layer applied.
  3. BrandThe scripted IceCat→Cryolite pass renames and re-arts the tree.
  4. PatchApply the Cryolite patch layer on top of the pristine branded tree.
  5. BuildCompile with the official release configuration via ./mach build.
  6. TestRun the smoke gate. Failures stop the line.
  7. PromotePack the blessed dist/bin into cryolite/dist/<version>/.
$ ./fetch-icecat.sh && ./cryolite-release.sh FORCE_CYCLE=1

Full pipeline documentation →

Get Cryolite

140.9.1-gnu1 latest promoted base

Binaries, checksums and per-cycle archives live on the download server. Launch with a dedicated profile directory — your data should live outside the build tree, just like ours does.

Open Downloads Install guide