ToolNest guide
How to format and validate JSON safely
Paste JSON, catch syntax errors, and copy clean output without installing a desktop editor.
Recommended tool
Open the matching ToolNest utility →Common JSON mistakes
Trailing commas, single quotes, missing braces, and unescaped line breaks are the most common reasons APIs reject JSON payloads.
Fast validation steps
Paste the payload, format it, read the error if parsing fails, then copy the formatted output into your API client, config file, or documentation.
When not to paste data
Do not paste production secrets, private tokens, or sensitive customer records into any public web tool. Use local tooling for those cases.