Multi-cool is a Ruby on Rails project that includes a variety of tools that I use in a daily basis. For the fun of it I recreated them and added them in a single project.
When you try to beautify an invalid json, the user's text is replaced by the sample/default text. Thus, the user loses any changes he may have made.
It would be nice and useful to keep the user's text and maybe add a "Clear" button, in case the user wants to clear the box.