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Free JSON Formatter and Validator
Format, validate and minify JSON with clear error messages that show the line and column. No sign-up, no upload.
Everything runs in your browser. Your JSON is never uploaded or stored.
How to format JSON
Paste your JSON into the left box. If it is valid, the formatted version appears on the right straight away and you can copy it or download it as a file. If it is not valid, you get a message that points to the line and column of the first problem. Switch between Beautify and Minify, and choose the indentation you prefer.
Fixing common JSON errors
Most errors come from the same few mistakes. A trailing comma after the last item is not allowed in JSON. Keys and text values must use double quotes, not single quotes. Comments are not part of JSON. Every opening brace or bracket needs a matching closing one. Values such as undefined and NaN do not exist in JSON. The error location usually points just after the actual mistake, so look at the characters right before it.
Beautify, minify and sort keys
Beautify adds line breaks and indentation so a person can read the data. Minify removes all spaces and line breaks to make the smallest possible text, which is useful for sending data or storing it. Sorting keys puts object keys in alphabetical order, which makes two JSON files easier to compare.
Your data stays private
JSON often contains API responses, settings and customer records, so nothing here is uploaded. The formatting runs in your browser, which also means there is no size limit set by a server.
FAQ
Yes. There is no sign-up and no limit on how much JSON you format.
No. It is parsed and formatted inside your browser and never leaves your device.
Check for a trailing comma, single quotes, an unquoted key or a comment. These are valid in JavaScript but not in JSON. The line and column in the message show where parsing stopped.
Numbers above 9007199254740991 lose precision because JavaScript cannot store them exactly. If exact big numbers matter, keep them as text in quotes.