The last version of Firefox for Mac OS 10.11 is the Extended Support Release of Firefox 78, which is pretty close to retirement. You can still get it from the following page -- make sure to choose 78.15.0esr and not the newer one. https://www.mozilla.org/firefox/all/#product-desktop-esr <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-10-12-11-08-54-c019f7.png" Unfortunately, there won't be any further updates. Any chance you can update Mac OS on your iMac? References: * [[Firefox Mac OS X 10.9, 10.10 and 10.11 users move to Extended Support Release]] * [[How to download and install Firefox on Mac]]

Moved from Firefox for iOS to desktop Firefox section since you are looking to install Firefox on Mac OS X and not on a iPhone or iPad as they use iOS.