Firefox Version 30-39 ((exclusive)) Today
It was the first version where Mozilla openly admitted that "Web standards compliance must accelerate." For end users, v30 felt like a stability patch—few new front-end features, but crash rates dropped 8% from v29.
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.
Immediately after v39 came (August 2015), which introduced multi-process (e10s) for a small test audience. Then Firefox 48 dropped plugin support for everything except Flash. And finally, Firefox 57 (Quantum) changed everything. The 30–39 range was the final era of the old-school, single-process, XUL-addon Firefox. firefox version 30-39
The final chapter of this range, Firefox 39, was a polish release. It disabled insecure TLS 1.0 fallback for banking websites and removed entirely. The most user-visible change was improved MacBook trackpad sensitivity and a better drag-and-drop for downloads .
Introduced support for GStreamer 1.0 on Linux and a new sidebar button for faster access to bookmarks and history. Importantly, it changed plugin behavior so that most plugins (except Flash) were no longer activated by default for security. It was the first version where Mozilla openly
Integrated Native DRM (Adobe Content Decryption Module) for the first time to allow playback of protected video content (like Netflix) without third-party plugins like Silverlight.
A "Panic" feature allowing users to quickly clear recent browsing history (5 mins, 2 hours, or 24 hours) with one click. OneCRL (v37): If one tab crashed, the whole browser went down
The era of (June 2014 – July 2015) marked a pivotal transition for Mozilla. This period saw the introduction of the modern "Australis" interface, a heavy focus on user privacy, and the implementation of groundbreaking web technologies like HTTP/2 and native DRM support. Firefox 30 – 33: Refinement and Performance
Version 30 added the Box Model Highlighter , while version 39 introduced drag-and-drop for nodes in the Inspector markup view.