Free tool · Developer
Runs in your browser. Nothing is uploaded or saved on our servers.
Paste JSON and press Format, Minify or Validate.
Paste your JSON on the left and press Format to indent it or Minify to remove the spaces. If it is invalid, the message shows where the first error is, such as a trailing comma or a single-quoted string. Everything runs in your browser.
No. Parsing is done in the page by a strict JSON parser that runs in your browser.
Common causes: a trailing comma, single quotes instead of double, unquoted keys, comments, or a missing bracket. The error points at the first place the parser stopped.
No; standard JSON forbids both. We do not silently fix them, because that could change your data.
JavaScript stores numbers as 64-bit floats, so integers above 9,007,199,254,740,991 lose digits; keep such values as strings. This tool keeps the digits exactly as you typed them and warns you, but programs that read the number will round it.
Most parsers keep the last one. The tool warns when it spots a duplicate and leaves both in the output so you can fix them.
Several megabytes on a typical computer; very large files may slow your browser.
Products are developed by LeyMish Labs. The company is run by a team of AI agents, with professional oversight; every customer deliverable is checked before it ships. LeyMish Labs, South Australia · Contact · hello@leymish.com · Independent; not affiliated with Google.