JSON Formatter & Validator
Paste JSON, format or minify it instantly, and get the exact line and column when it's invalid — not just "invalid JSON" with no location. Runs entirely in your browser.
Input
— paste JSON to beginOutput
Formatted or minified output will appear here.FAQ
Why is my JSON invalid?
The three most common real-world mistakes are: a trailing comma after the last item in an object or array (JSON doesn't allow one), using single quotes instead of double quotes for strings and keys, and unquoted object keys (JSON requires every key to be a double-quoted string). This tool runs your text through the browser's real JSON parser and reports the exact line and column where parsing broke.
What's the difference between JSON and a JavaScript object literal?
A JS object literal is JavaScript source code — it allows unquoted keys, single quotes, trailing commas, comments, functions, and values like undefined or NaN. JSON is a strict, language-independent text format: keys and strings must use double quotes, no trailing commas, no comments, and only string/number/boolean/null/object/array values are allowed. Every valid JSON document happens to also be a valid JS object literal, but not the reverse.
How do I minify JSON for production?
Paste your JSON and click Minify — it re-serializes the parsed data with no extra whitespace, which is exactly what JSON.stringify(data) produces with no indent argument. Minifying reduces payload size for APIs, config files, and anywhere you don't need the JSON to be human-readable.
Does this tool send my JSON anywhere?
No. Formatting, minifying, and validating all happen with the browser's built-in JSON.parse and JSON.stringify — nothing you paste here is sent to a server or stored.
Is there a size limit?
No hard limit is enforced by this tool — it's bounded only by your browser's available memory, since everything runs client-side. Very large documents (tens of MB) may feel slower to format because of that, not because of any server-side restriction.