Firefox Legacy

Firefox Legacy was an unofficial modified version of Mozilla Firefox that worked on older Mac OS X versions, including 10.6 Snow Leopard, 10.7 Lion, and 10.8 Mountain Lion.

As of 2021-10-24, Firefox Legacy is no longer supported. It has become increasingly challenging to update it to a more modern Firefox version, and I no longer use it myself.
It is no longer available for download, to incentivize the use of other currently supported browsers. The information below and the source code are still available for reference.

If you need an up-to-date browser on your older Mac, I would recommend installing Linux instead of using an unsupported and insecure operating system. There are many tutorials online on how to do this. You can even dual-boot with Mac OS X if you need to use Mac software.

If you still want an up-to-date browser for older Mac OS X versions, try:

• Chromium Legacy for OS X 10.7 and later versions. It is no longer being updated for unknown reasons, but should still be compatible with the vast majority of websites.
• InterWeb for Mac OS X 10.6 (direct link to releases). InterWeb incorporates some of the patches I made to Firefox 52 to allow it to run on Mac OS X 10.6.
• Pale Moon still supports Mac OS X 10.7 and later versions, but it now requires a CPU wth AVX support, which means that it will only work on Macs from 2011 and later (except the 2012 Mac Pro), which can all run at least OS X 10.13. This limits its usefulness on older OSes.

You may need to open this direct link to download Chromium Legacy; no browser for OS X 10.7-10.8 other than Chromium Legacy, InterWeb, or Pale Moon is able to display GitHub correctly.
To enable Google sync in Chromium Legacy, quit the browser, then enter the following command in Terminal (it is one long line):

open -a /Applications/Chromium.app --args "--oauth2-client-id=77185425430.apps.googleusercontent.com --oauth2-client-secret=OTJgUOQcT7lO7GsGZq2G4IlT"

Chromium Legacy will open; log into your Google account. You will not need to run the command again unless you log out.

OS X 10.8 Mountain Lion

Download no longer available, see above

Source Code

Final version for OS X 10.8 Mountain Lion: 71.0p2 (2020-09-15)
IMPORTANT NOTE ABOUT UPDATING TO v71: A new Firefox profile will be created when you update from earlier versions to version 71.0. To restore your previous data, type "about:profiles" in the address bar, then find your previous profile (if you can't tell which, try each one) and set it as default. Then, restart Firefox Legacy. I apologize for the inconvenience; the cause of this issue is not known.

OS X 10.7 Lion

Download no longer available, see above

Source Code

Final version for OS X 10.7 Lion: 68.12.0p3 (2021-01-24)
Now featuring support for numerous newer web standards, including Push, Service Workers, Feature Policy, ResizeObserver, Promise Rejection Events, more of the Animations API, and several CSS features. This should improve compatibility with many websites.
For security and privacy reasons, starting in version 68.12.0p3, support for TLS 1.0 and 1.1, HPKP, and the Battery API is disabled.

OS X 10.6 Snow Leopard

Only Firefox 52.9.1 is available for OS X 10.6 Snow Leopard; it will receive no further updates, in part due to technical limitations of the OS.
Note: the program is called "Nightly" due to licensing restrictions prohibiting the use of the official Firefox branding.

Download no longer available, see above

Source Code

Final version for OS X 10.6 Snow Leopard: 52.9.1p1 (2020-04-11)

Firefox Legacy speaks your language!

Any of the language packs for the matching official Firefox version are supported.

• Language packs for version 71
• Language packs for version 68
• Language packs for version 52
• List of language codes (to help you locate the right file to download)

Small areas of the about screen and the help menu that are specific to Firefox Legacy will remain untranslated.

Known Issues

• Potential problems with displaying right-to-left languages on OS X 10.7 (an API is not implemented)
• The crash reporter does not work on OS X 10.7 or 10.8 (it itself crashes)
• A useless empty share menu is visible on OS X 10.7
• The sandbox (a security feature intended to protect you from malicious websites) does not work, and has been disabled
• On OS X 10.7, the browser crashes when the camera or microphone are used
• WebGL does not work on some older Macs
• Some buttons are invisible on Google Calendar, WordPress, and other sites that use font-based icons
• DRM (Encrypted Media Extensions/Widevine) does not work
• Version 68.12.0 only: Screen capture does not work and has been disabled
• Version 71.0 only: The progress bar is not visible on the icons of downloading files in the Finder