JSON Formatter
Format, minify and validate JSON, and find syntax errors fast. Everything happens on your device.
Your JSON is processed in your browser and is not uploaded.0 characters, 0 B. Up to 5.0 MB, nested up to 200 levels.
How to format and validate JSON
- Paste JSON into the box, or choose or drop a UTF-8 file.
- Pick an indentation, then press Format to pretty-print, Minify to remove whitespace, or Validate to only check it.
- If the JSON is invalid, the message gives the line and column. Press Show error position to jump to it.
- Copy the result or download it as formatted.json or minified.json.
What this tool does and does not do
It checks strict JSON and changes only whitespace, so your values are never reinterpreted or rounded. It does not repair broken JSON, sort keys, or accept JSON5 and JSON with comments. Your original text is never changed until you edit it yourself.
Frequently asked questions
Is my JSON uploaded?
No. Your JSON is processed in your browser and is not sent anywhere or saved. It is gone when you close or reload the page.
Does formatting change my data?
No. Only whitespace changes. Numbers, strings, escapes and key order are kept exactly as written, so values such as 9007199254740993 or 1.2300e+02 are not rounded or rewritten.
What counts as valid JSON?
Strict JSON as defined by RFC 8259. Comments, trailing commas, single quotes, unquoted keys, NaN and Infinity are not valid and are reported with their position.
What happens with duplicate keys?
They are valid JSON syntax, so the input is accepted and both entries are kept, with a warning. Many parsers silently use only the last value.
What are the limits?
Input up to 5.0 MB and nesting up to 200 levels. Larger inputs are refused rather than truncated.
Which files can I open?
UTF-8 text files such as .json. A leading byte order mark is removed. Files in other encodings are rejected with a message.
How was this tool?
Help us improve JSON formatter.
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