Permafrost

A local mirror of the opensource Javascript libraries hosted by ajax.googleapis.com. This extension intercepts requests to ajax.googleapis.com and loads those files from your local disk.

ajax.googleapis.com is a free service provided by Google which hosts very common open source Javascript libraries. This saves sites from each providing their own copy of those libraries, which in the long run is faster for the user. That's a great initiative and works well, but sometimes you can't or just don't want to be that dependent on Google. This extension has all files ajax.googleapis.com has, but transparently loads them from your own system.

For more information about googleapis:
https://developers.google.com/speed/libraries/devguide

For the sourcecode of this extension:
https://github.com/alicebob/permafrost