DEVELOPER TOOL
JSON Formatter & Validator
Format, validate, and minify JSON with clear error messages.
About this tool
Paste any JSON to check whether it's valid and see it reformatted with clean, readable indentation. If something's wrong, the error message tells you what and roughly where, instead of leaving you to guess. Minify strips all unnecessary whitespace for the smallest possible output.
Everything is parsed and formatted locally in your browser — nothing is uploaded.
Frequently asked questions
- What counts as invalid JSON?
- Common issues include trailing commas, single quotes instead of double quotes, unquoted keys, and missing brackets — JSON is stricter than JavaScript object literals.
- Does formatting change the data?
- No — formatting only changes whitespace and indentation. The underlying values, keys, and structure are preserved exactly.
- Is there a size limit?
- Very large JSON (multiple megabytes) may be slow to format in-browser since there's no server doing the work — for most everyday JSON it's instant.