JSON Formatter & Validator
Paste JSON to pretty-print, minify, and validate it instantly, with clear error messages if it's broken.
Format, validate, and minify JSON instantly
Paste any JSON — an API response, a config file, a log line — and this tool pretty-prints it with proper indentation, or strips it down to the smallest possible size with Minify. If the JSON is invalid, you get a clear error message instead of a silent failure, including where in the text the problem is.
Common JSON mistakes this catches
- Trailing commas after the last item in an object or array (valid in JavaScript, invalid in strict JSON).
- Single-quoted strings or keys instead of double quotes.
- Unquoted object keys.
- Missing commas between items, or an extra comma.
- Unescaped control characters inside a string.
Frequently asked questions
Why does it say my JSON is invalid when it looks fine to me?
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 and strings, or an unquoted key — all valid in JavaScript object literals but not in strict JSON. The error message includes the position where parsing failed to help you find it.
What's the difference between Format and Minify?
Format (pretty-print) adds indentation and line breaks to make nested JSON easy to read. Minify strips all unnecessary whitespace to produce the smallest possible file size, which is what you want for production API responses or config files.
Can I change the indentation size?
Yes — pick 2 spaces, 4 spaces, or a tab character before formatting, whichever matches your project's style.
Is my JSON data uploaded anywhere?
No — parsing, formatting, and validation all happen directly in your browser using the built-in JSON object. Nothing you paste is ever sent to a server, which matters if your JSON contains API keys, tokens, or other sensitive data.