Formateur & validateur JSON

JSON is the format most APIs speak, but it is unforgiving: one trailing comma or a single quote in the wrong place and the whole document fails to parse. This formatter reads your JSON, tells you exactly where it breaks, and rewrites it with consistent indentation so you can actually read it. Minify does the reverse when you need the smallest possible payload.

Comment l'utiliser

1. Paste raw JSON into the input box — an API response, a config file, a log line.
2. Press Format to expand it with two-space indentation, or Minify to strip every optional byte.
3. If the JSON is invalid you get the parser error and the position it failed at, instead of a silent blank.
4. Copy the result, or send it straight to a paste if you need to share it with someone.

Questions fréquentes

Is my data sent to your server?

No. Formatting runs entirely in your browser using the built-in JSON parser. Nothing leaves your machine unless you explicitly click "Share as paste".

Why does my JSON say "Unexpected token"?

Almost always one of four things: a trailing comma after the last item, single quotes instead of double quotes, unquoted object keys, or a stray comment. JSON allows none of these, even though JavaScript does.

Can it handle large files?

It handles anything your browser can hold in memory — typically several megabytes without trouble. Very large files may briefly freeze the tab while parsing.

Does formatting change my data?

No. It parses the JSON and re-serialises the same values. Only whitespace changes. Note that key order is preserved but duplicate keys collapse to the last one, because that is how JSON parsing is defined.