One of the major features of Firefox that keeps users glued to the browser are it’s vast array of extensions or browser add-ons. Unfortunately, our dependency on those few critical add-ons keep us from aggressively upgrading to the latest Firefox release. Not running the latest and greatest software is generally taboo in the enthusiasts culture. However, if the jump is made too early we are often left with buggy and broken extensions which have yet to be adjusted to function cleanly in the new release. This uncomfortable situation will be forth-coming later this year, when Firefox pushes out version 4.0 – currently in a multi-stage beta release cycle. In a perfect world, all the major extensions will be compatible upon it’s release but that’s often not the case. Worse, for the niche extensions they may never be updated.

Unfortunately, there does not exist a quick and efficient way to ensure what add-ons will break upon the upgrade short of just making the jump and picking up the pieces afterward. Clearly not an ideal situation!

Here are a few of the add-ons installed on one of my Firefox profiles.

Is It Compatible? is a simple Firefox extension that queries the Mozilla add-on repository and returns what version range the extension is compatible with. Notice how it has changed my add-ons window from above to what it is now below:

You can see that Greasemonkey is not yet compatible with the beta releases of Firefox 4 – it shows a range of 1.5-3.6.*. If you rely on just a few key add-ons, then browsing the Mozilla repository directly isn’t much of a burden but any more than a handful, it quickly becomes cumbersome. Is It Compatible? is then a godsend for you.

Should you feel more adventurous, it is possible to force Firefox to run incompatible extensions but the actual results can vary – some add-ons just have a version-check string that prevents them being enabled in Firefox releases it can’t recognize. Others can be much more complicated; for these it will ultimately require the developer to update the extension.

Download Is It Compatible?