Does my JSON get sent to a server?

No. Formatting and validation use JavaScript's built-in JSON.parse and JSON.stringify, running entirely in your browser. Your data never leaves your device — important when you're pasting API responses with auth tokens or PII.

What does 'minify' do?

Minify removes all whitespace and newlines to produce the smallest valid JSON. Useful for production payloads — smaller bytes = faster network transfer.

How big a JSON can I format?

Modern browsers handle 50-100 MB of JSON without issue. For larger files, expect a slight pause while the browser processes.

JSON Formatter & Validator — Free, In Browser, No Upload

Frequently Asked Questions

Is my JSON private?

Yes. Formatting/validating happens entirely in your browser via JSON.parse and JSON.stringify. Nothing is sent to any server. Safe for API responses with tokens, customer data, anything sensitive.

Why is my JSON invalid?

Most common causes: trailing commas (not allowed in JSON), single quotes instead of double, unquoted property names, JavaScript-style comments. The error message points to the position of the problem.

What's the difference between format and minify?

Format adds indentation and newlines for readability. Minify removes all whitespace to produce the smallest valid JSON — used in production payloads.