Developer · Free Tool
JSON Formatter & Validator
Format, beautify, validate, and minify JSON with clear error messages pointing at the problem.
About this tool
Paste JSON to pretty-print it with your preferred indentation (2 spaces, 4 spaces, or tabs), minify it to a single compact line, and validate it — invalid JSON produces a clear error message with the position of the problem.
Formatted JSON is dramatically easier to read when debugging API responses, editing configuration files, or reviewing webhook payloads. Minified JSON saves bytes in production payloads.
Common uses
- Pretty-print a one-line API response so it is actually readable
- Validate a config file after hand-editing it
- Minify JSON before embedding it in a data attribute or payload
Frequently asked questions
Why is my JSON invalid when it looks fine?
The usual culprits: trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and comments — none of which strict JSON allows. The error message points at the offending position.
Is JSON with comments valid?
No. Standard JSON has no comment syntax. Variants like JSONC allow them, but a strict parser (like this validator, and most APIs) will reject comments.
Is my data uploaded to a server?
No. This tool runs entirely in your browser using JavaScript — nothing you type is transmitted, logged, or stored anywhere. You can even use it offline once the page has loaded.