Firefox version 78 is the last supported Firefox version for Mac users of OS X 10.9 Mavericks, OS X 10.10 Yosemite and OS X 10.11 El Capitan. These users will be moved to the Firefox Extended Support Release (ESR) channel by an application update. This will provide security updates until the next ESR update in July 2021, after which the affected users will no longer receive security updates.
While Apple does not have a public policy governing security updates for older OS X releases, their ongoing practice has been to support the most recent three releases. The last security update applicable to OS X 10.11 was made available in July 2018. Unsupported operating systems do not receive security updates, have known exploits and can be dangerous to use, which makes it difficult to maintain Firefox on those versions.
It is scheduled to be replaced by Firefox 49.0 on September 13, 2016. At that point, Mac users using OS X 10.6 Snow Leopard, 10.7 Lion, and 10.8 Mountain Lion will be left behind by the current versions of Firefox. It will be a sad day, as Firefox is the last major browser to support Mac OS X 10.6 through 10.8. Mac OS X 10.1 (Firefox 1.0.8), OS X 10.2 and OS X 10.3 (Firefox 2.0.0.20), Mac OS X 10.4 (Firefox 3.X), Mac OS X 10.5 or above (Current Version). Press the 'Download Now' button to download firefox for mac os x 10.5.8 installer. The whole process will just take a few moments. If it happens that the download gets blocked by your browser or Chrome, know that this occurs because it's falsely detected as a virus. This is why we highly recommend that you use Safari instead when downloading.
Firefox Download For Mac Os X 10.6 8
Up until July 2021, we will be updating affected users with critical security updates through the Firefox ESR channel to help retain the best possible security. After this, no security updates will be provided.
Firefox For Mac Os X 10.5 8 Download
If you want to keep your Firefox version up to date, you will need to upgrade your operating system to macOS 10.12 or higher. Older versions that are not supported by Apple are unreliable and unsafe to use, which also makes it difficult to maintain Firefox on those versions.