JSON Formatter & Validator — Free, Instant, Private

How to format and validate JSON

Paste your JSON into the left editor. The tool validates it on the fly — if the JSON is malformed, you'll see an error message describing exactly what's wrong. Click 'Format' to indent and beautify it with 2-space indentation.

Use 'Minify' to strip all whitespace and compress the JSON into a single line — useful when you need compact JSON for API payloads or configuration files where size matters.

Your data never leaves your browser. The formatter runs entirely in JavaScript using the browser's built-in JSON parser — there is no server involved and nothing is stored.

Frequently asked questions

Is my JSON data sent anywhere?

No. The formatter runs entirely in your browser using JavaScript. Your data never leaves your device and is never sent to any server.

What does JSON validation check?

The validator checks that your input follows the JSON specification: properly quoted keys, valid value types (string, number, boolean, null, array, object), matching brackets and braces, and no trailing commas.

What is the difference between formatting and minifying JSON?

Formatting (also called pretty-printing or beautifying) adds indentation and line breaks to make JSON human-readable. Minifying removes all unnecessary whitespace to make the JSON as compact as possible — useful for reducing payload size in APIs and config files.

Can this handle large JSON files?

Yes. Processing happens entirely in your browser's JavaScript engine and can handle JSON files up to several megabytes without issues. Very large files (tens of megabytes) may be slower depending on your device.

Why use a browser-based JSON formatter instead of a desktop app?

A browser-based formatter requires no installation and works on any device. Since this tool is fully client-side, your data stays private — unlike server-side formatters that process your JSON on their servers.