Text & code · runs locally
JSON formatter & validator
Paste messy JSON, get it neat — with a precise error message and line number when it's broken.
Runs on your device
No uploads, ever
Free, no account
- 1Paste your JSON
Or a piece of it — the tool tells you where the syntax breaks, line included.
- 2Format or minify
Two spaces, four spaces or tabs for readability; one line for feeding to something else.
- 3Copy or download
Copy button for the clipboard, or take it as a .json file.
Questions people actually ask
What counts as invalid JSON?
Trailing commas, single quotes, unquoted keys, comments — the things that make JSON look like JavaScript but aren't. The error message points at the line and character.
Can it handle large files?
Very large — megabytes of JSON format in well under a second since it's a genuine parser, not a regex trick.