JSON5 is an extension of the JSON file format designed to be more user-friendly for manual editing (config files, etc.) but not for machine-to-machine communication. Despite some controversy, it has gained popularity with over 65M downloads per week, used by major projects like Chromium and Next.js. JSON5 is fully compatible with JSON and a subset of ES5. It supports features like single quotes, trailing commas, and more. The API includes methods like JSON5.parse() and JSON5.stringify(). A CLI is available for converting JSON5 to JSON and validating syntax. Contributions are welcome with tests and linting. JSON5 aims to align closely with ES5 and is maintained by Jordan Tucker.
https://json5.org/