[navitronic]

Inherited some terrible javascript from a colleague or otherwise: http://jsbeautifier.org

[navitronic]

I should clarify, I mean terribly formatted.

Also works great for displaying JSON in a consistent way, useful for visualising and understanding object hierarchies.

[thisisblurry]

http://jsonlint.com also does a great job of not only pretty-printing (valid) JSON, but also checking it for any errors.