JSON Formatter
Format, validate and minify JSON instantly. Runs entirely in your browser, and your data is never sent anywhere.
🔒 Your JSON is parsed on your device and never sent anywhere.
Paste JSON to pretty-print it with the indentation you prefer, minify it down to a single line, or find out exactly where it is malformed. Parsing happens in your browser using the built-in JSON engine. Nothing is transmitted, logged or stored.
Most online JSON formatters POST your text to a server. That is a genuine problem when the JSON is an API response containing tokens, customer records or internal identifiers. Pasting that into someone else's web app is a data disclosure, even if nobody ever looks at it.
How to format JSON
- Paste your JSON into the input box above.
- Choose an indentation style: 2 spaces, 4 spaces, or tabs.
- Click Format to pretty-print it, or Minify to strip all whitespace.
- Copy the result to your clipboard, or download it as a .json file.
What makes this different
- Your JSON never leaves the browser, so it's safe for tokens, API responses and internal data.
- Validation errors report the exact line and column, not just a character offset.
- Minify mode for shrinking payloads; pretty-print for reading them.
- No length limit beyond your browser's memory, and it works offline.
Frequently asked questions
- Is my JSON sent to a server?
- No. Formatting and validation use the JSON parser built into your browser. You can disconnect from the network and this tool keeps working.
- Why does it say my JSON is invalid?
- The most common causes are trailing commas after the last item, single quotes instead of double quotes, comments (which standard JSON does not allow), unquoted keys, and unescaped line breaks inside strings. The error message points at the line and column where parsing stopped.
- What does minify actually do?
- It removes every byte that is not required (indentation, newlines and spaces between tokens), producing identical data in the smallest valid form. It is useful for shrinking config files and network payloads.
- Does formatting change my data?
- No. The tool parses your JSON and re-serialises it, so the values are identical. Key order is preserved; only whitespace changes. One thing to be aware of: duplicate keys in the input collapse to the last one, because that is how JSON parsing is defined.