I didn’t find a free text editor to indent code, but I found this powerful beautifier. I use it to format js or json code. For example, Firebug can track ajax calls and shows the json response (unformatted). With this tool you can paste the response body, indent it, and finally read the content without going crazy…
Did you check the following site:
Cool also the site you specified, but for indentation works better the one I specified.
Other utilities are useful too!