Beautify, unpack or deobfuscate JavaScript, make JSON/JSONP readable, etc..
Beware, large texts tend to mess up heavily in recent Chromes for reasons yet unknown. I'll look for the reason and the solution, but if you'd take a time to look into this problem as well, that would be awesome. Thanks!
All of the source code is available on the github, and we have a command-line version and a python library as well.
JSBeautifier is — and always will be — completely free and open, and your thanks, flattrs and donations are very heartwarming — thank you all so much!
Browser extensions and other uses:
A bookmarklet (drag it to your bookmarks) by Ichiro Hiroshi to see all scripts used on the page,