Almost reversible JSON -> XML -> JSON converter
You might find this useful if your project requirements like configuration file format are specified and updated right after project finished and you cannot do anything about it. This page uses json2xml.js (with minor changes for better handling of formatted XML) and CodeMirror.
Why "almost" reversible? AFAIK it has one flaw: when parsing XML (using browser built-in parser - this is unfortunately how XML parsing works) newlines in text are normalized to "\n".