JSON Formatter & Validator
Format, validate and minify JSON in your browser. 2/4/tab indent, sort keys, exact line and column errors, and big-integer safe mode. Nothing is uploaded.
Paste JSON or drop a .json file — it is parsed by your own browser and never uploaded.
Formatting and validation run with your browser’s own JSON parser. Nothing is uploaded. · Ctrl/Cmd + Enter to re-format
Result
Paste JSON on the left, or drop a .json file.
How to use
- Paste JSON into the left box, drop a .json file, or press ‘Load sample’ to try it out.
- Choose an Indent: 2 spaces, 4 spaces, Tab, or Minify to strip every space.
- Tick ‘Sort keys’ (and nested objects), or ‘Preserve big integers’ to keep digits past 2^53.
- If the JSON is invalid, read the line and column in the error and use the go-to-line button.
- Copy the formatted JSON from the output box, or press ‘Download .json’ to save it.
FAQ
Is my JSON uploaded to a server?
No. Formatting, validation and minifying all run in your browser with the native JSON parser. There is no upload and no "save" feature — the page never sends your data anywhere. Open DevTools → Network and watch: nothing leaves after the page loads.
Why do my large ID numbers change after formatting?
JavaScript numbers lose precision above 9,007,199,254,740,991 (2^53−1), so Snowflake-style IDs get rounded. Turn on "Preserve big integers" and we keep those literals exactly as they appear, as strings.
Can I load JSON from a URL?
No, and that is deliberate. Fetching a URL would require our server to make the request for you, which breaks the promise that your data never leaves your browser. Paste the JSON or drop the file instead.
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