JSON Formatter & Validator

JSON (JavaScript Object Notation) is a lightweight data format used to exchange data between applications and APIs. Minified JSON has all whitespace removed for efficiency, making it hard to read. Formatted JSON adds indentation and line breaks to make it human-readable without changing its meaning.

Yes, completely. All formatting happens in your browser using JavaScript. No data is sent to any server. This tool works entirely offline once loaded — you can even disconnect from the internet and it will continue to work. We have no logs of what you paste.

The most common JSON errors are: trailing commas after the last item in an object or array (not allowed in JSON), single quotes instead of double quotes for strings, unquoted keys (all keys must be in double quotes), and comments (JSON does not support // or /* */ comments). JavaScript objects allow these, but strict JSON does not.

JSON is a strict text format — all keys must be in "double quotes", values can only be strings, numbers, booleans, null, arrays, or objects. JavaScript objects are more flexible — they allow unquoted keys, single quotes, trailing commas, functions as values, and comments. JSON is essentially a strict subset of JavaScript object syntax.

In JavaScript: wrap JSON.parse() in a try-catch block. If it throws, the JSON is invalid. In Python: use json.loads() inside a try-except block catching json.JSONDecodeError. In online tools like this one, invalid JSON will show an error message explaining exactly where the syntax issue is.