Download Firefox 12-51 52 Esr ((exclusive)) Here

These are "Rapid Release" versions. While they are no longer supported with security updates, they are sometimes sought for testing or specific legacy software requirements. Firefox 52.9.0 ESR:

: Select your locale (e.g., en-US/ for English US). Download Firefox 12-51 52 Esr

You can browse the full directory of every version ever released on the Mozilla FTP Archive . Key Version Differences Version Range Key Features / Support v12 – v51 These are "Rapid Release" versions