Firefox

Mozilla‘s browser, and the only mainstream browser still shipping an engine that is neither Chromium nor WebKit. It runs on Gecko, with SpiderMonkey as its JavaScript engine — and Firefox’s own interface is largely JavaScript running on that engine, not native UI code.

Security architecture is where the recent engineering went. Content is split across processes, and Fission (2021) made that split per-site: a content process loads and executes one site’s instructions and nothing else, which is what closes the Spectre/Meltdown class of cross-site reads. Source: Mozilla’s platform docs.

Share: 3.34% worldwide in July 2026 (statcounter-browser-share), fourth behind Chrome, Safari and Edge, and ahead of Samsung Internet and Opera.

Where it sits in this spoke’s three currents

Firefox is not an ai-browser and has not been positioned as one. It belongs to the privacy-first current by history rather than by campaign — the position brave and vivaldi now market aggressively, Firefox held first and quietly. vivaldi is the sharper anti-AI statement today.

Its real role here is structural. Every engine-diversity claim in this spoke — ladybird, Falco, kitesurf — is about a young engine with no users. Firefox is the control case: an independent engine with a full standards implementation, two decades of shipping, and a shrinking single-digit share. It shows that engine independence does not, by itself, buy a browser its market back. zen is the counter-current — a Gecko browser gaining attention on interface design rather than on engine politics.

Open thread

The spoke has no source on Mozilla’s funding position, which is the fact the diversity argument actually turns on: the Google search deal has paid for most of Gecko’s development for years, so the independent engine is funded by the company that ships the dominant one. Recorded in synthesis as a gap, not a claim.