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
DevToys - A collection of converters, formaters, encoders, generators and other tools for your Windows desktop.
JSONLint - JSON Lint is a web based validator and reformatter for JSON, a lightweight data-interchange format.
SafeUtils - SafeUtils: Native MacOS, Linux and Windows desktop application with 110+ carefully crafted tools for yours and your teams everyday work with sensitive data in various formats.
JSON Editor Online - View, edit and format JSON online
CyberChef - The Cyber Swiss Army Knife