Note for advanced users: Creating a policies.json file inside a folder named distribution within the Firefox installation directory and adding "policies": "DisableAppUpdate": true will permanently lock updates at the system level. Best Practices for Running Legacy Browsers Safely
Maintained deep compatibility with Windows 2000 and early XP service packs. Standardized early HTML5 elements and CSS3 animations. Firefox 22 to 37: Performance and WebRTC Integrated WebRTC (Web Real-Time Communication) by default. Download Firefox 12-51 52 Esr