JSON Formatter & Validator

Format, minify and validate JSON with precise error messages — right in your browser.

How to use

  1. Paste your JSON in the input field — from an API response, a config file or a log line.
  2. Click "Format" for readable, indented output, or "Minify" for the compact single-line version.
  3. If the JSON is invalid, the exact parser error is shown so you can fix it. Copy the result with one click.

About this tool

JSON (JavaScript Object Notation) is the standard data format of the modern web: APIs, configuration files, logs and databases all speak it. But machine-generated JSON usually arrives as a single unreadable line. This formatter turns it into properly indented, human-friendly output — and does the reverse when you need to ship a compact payload.

Validation uses the browser's native JSON parser, the same engine your JavaScript code runs on. That means the verdict you get here is exactly the verdict your application will get: if it parses here, it parses there. Error messages include the parser's own description of what went wrong, which usually points at the offending character.

Your data never leaves the page. Formatting, minification and validation all run locally, which makes this tool safe even for JSON containing tokens, keys or personal data — nothing is uploaded, logged or stored anywhere.

Frequently asked questions

Is my JSON sent to a server?

No. Parsing and formatting run entirely in your browser with the native JSON engine. The page makes no network requests with your data.

What indentation is used?

Two spaces by default, with a 4-space option. Minify removes all insignificant whitespace.

Why is my JSON invalid if it works in JavaScript?

JavaScript object literals accept single quotes, unquoted keys and trailing commas — strict JSON does not. The formatter follows the JSON standard (RFC 8259), like any API will.

Is there a size limit?

Only your device's memory. Files of several megabytes format fine in modern browsers.

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