JSON Formatter & Validator
Beautify, minify, and validate JSON — with clear error messages when something's wrong.
About the JSON Formatter
A JSON formatter takes compact or messy JSON — like a raw API response squeezed onto one line — and reformats it with consistent indentation so it's actually readable, or does the reverse and minifies it down for production use. Along the way it validates the JSON, pointing out exactly why it failed to parse if it's malformed.
This is a common step when debugging an API response, cleaning up a config file, or checking whether a JSON payload someone sent you is actually valid before using it.
Worked example
Example: pasting {\"name\":\"Ana\",\"active\":true} and clicking Format returns it spread across multiple indented lines with each key on its own row — much easier to scan than the single-line version, especially for deeply nested objects.
Frequently asked questions
- Why does it say my JSON is invalid when it looks fine?
- The most common causes are a trailing comma after the last item in an object or array, using single quotes instead of double quotes around keys/strings, or an unescaped quote inside a string — all valid in JavaScript object literals but not in strict JSON.
- What's the difference between formatting and minifying?
- Formatting (beautifying) adds indentation and line breaks to make JSON easy for humans to read. Minifying strips all unnecessary whitespace to make the file as small as possible — useful for production APIs or reducing file size, at the cost of readability.
- Is my JSON data sent anywhere?
- No. Parsing, formatting, and validation all happen locally in your browser using JavaScript's built-in JSON parser — nothing is uploaded to a server, so it's safe to paste sensitive API responses or config data.
- Does this support JSON5 or JavaScript object syntax?
- No, this tool validates strict, standard JSON only (as defined by json.org) — the same format used by REST APIs and config files. Comments, trailing commas, and unquoted keys will be flagged as errors, since those aren't valid JSON.