Quick Json Formatter is a tool for formatting and coloring raw JSON code. Very often if you use JSON generated by server side code it will be in a nice compact format but at the same time it will be quite hard to read it and possibly alter it. So the tool allows you to make your JSON more readable.
The tool is actually just a single simple HTML page with inline script and styles. There are no includes or dependencies. There is no server code so it will run on any operating system (Windows, Mac, Linux and what have you) under any modern browser, the best formatting I think is under Firefox, but it works fine with Internet Explorer and Safari.