JSONFormatter.org - Online JSON Formatter and JSON Validator will format JSON data, and helps to validate, convert JSON to XML, JSON to CSV. Save and Share JSON
JSON Editor Online - View, edit and format JSON online
JSONLint - JSON Lint is a web based validator and reformatter for JSON, a lightweight data-interchange format.
CodeBeautify - Online Tools like Beautifiers, Editors, Viewers, Minifier, Validators, Converters for Developers: XML, JSON, CSS, JavaScript, Java, C#, MXML, SQL, CSV, Excel
Text-Utils JSON Formatter - The JSON Formatter can be used to convert JSON to one line or format it using a specified level of indentation.
JSONedit - JSON editor for Windows and Wine with tree, list and text views.