But nestled in the mid-2010s, between the rapid-release wars and the Quantum revolution, lies a fascinating, often forgotten era: .
So the next time you see a Stack Overflow answer referencing Firefox 35 or an old enterprise guide requiring Firefox 31 ESR, remember: that’s the release that kept the open web alive, one bug fix at a time. firefox version 30-39
Do you still have to support Firefox 38 ESR in your organization? Share your war stories in the comments below. And if you found this deep dive useful, check out our article on Firefox 40–49: The Electrolysis Rollout. But nestled in the mid-2010s, between the rapid-release
Introduced in late 2014, allowing developers to debug Firefox OS devices and Cordova projects directly. Share your war stories in the comments below
Perhaps the most critical development in this range was the beginning of the multi-process architecture, known internally as Electrolysis (e10s). Before this, Firefox was a single-process application. If one tab crashed, the whole browser went down. If a website froze, your entire session froze. Beginning around versions 36 and 37, Mozilla started testing the separation of browser UI and web content into different processes. This was a monstrous engineering task that required rewriting how almost every add-on functioned. This period laid the foundation for the stability we take for granted in modern browsers.
The MDN Web Docs note that this era turned Firefox into a power-user's dream for debugging: