Download Firefox 12-51 52 Esr ^hot^ Jun 2026

To download legacy or Extended Support Release (ESR) versions of Firefox, such as version 52, you should use official Mozilla archives to ensure security and file integrity. Older versions like 12–51 are generally outdated and no longer receive security updates, so they should only be used in isolated or legacy environments. 🌐 Direct Download Links

ESR versions receive security patches without changing the core functionality of the browser. ⚠️ Critical Security Warning

This is the absolute final update for the 52 series, released in June 2018 to provide the last security fixes for older operating systems. 2. Where to Download Safely Download Firefox 12-51 52 Esr

Choose your preferred language code subfolder (e.g., en-US/ for English - United States).

Introduced silent background updates for Windows users. To download legacy or Extended Support Release (ESR)

It was the final version of Firefox to support NPAPI plugins like Silverlight, Java, and Adobe Acrobat.

Retained NPAPI plugin capabilities while the main release branch stripped them out. ⚠️ Critical Security Warning This is the absolute

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

Scroll to find your specific version (e.g., 52.9.0esr or 45.0 ). Select your target operating system: win32/ for 32-bit Windows win64/ for 64-bit Windows mac/ for macOS linux-x86_64/ or linux-i686/ for Linux distributions

Do you require a specific legacy like Java, Flash, or Silverlight?

If you install Firefox 52 ESR, you must immediately disable automatic updates. Otherwise, it will auto-upgrade to Firefox 60 ESR (which drops NPAPI support and will break your legacy plugins).