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
SmallDevTools - Handy developer tools with a delightful interface
JSON Editor Online - View, edit and format JSON online
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
JSONLint - JSON Lint is a web based validator and reformatter for JSON, a lightweight data-interchange format.
Profitable developer tools database - A database of 103+ hand-curated profitable developer tools