Since we implemented Add-ons Default to Compatible, most add-ons that were updated to work on Firefox 4 continue to work on the latest releases. The add-on compatibility problems we’ve had ever since have been minimal.

However, there are still a number of popular add-ons that weren’t updated for the switch to Firefox 4. People who still have these add-ons installed may be skipping Firefox updates because their add-ons are not compatible yet, and probably never will be. As we make a stronger push to move users away from old and potentially insecure Firefox versions, we need to make sure they don’t lose the add-ons they love.

Luckily, we have an amazing add-on developer community, where no abandoned add-on goes unforked. I spent a great deal of time looking for the most popular add-ons still in use on 3.6 and lower, as well as their best alternatives. Here they are.

I’d like to thank the developers of FireDownload, IE Tab and The Browser Highlighter for upgrading their add-ons between the time this list was compiled and the publication of this blog post.

Are there any other add-ons holding you back on Firefox 3.6 or older? Do you have other recommendations for alternatives? Let me know in the comments!