JSON Formatter

Format, validate, and minify JSON in your browser

This free JSON formatter pretty-prints, validates, and minifies JSON without sending a single byte to a server. Paste a raw API response, a configuration file, or a one-line blob and get clean, indented, readable JSON back instantly, or collapse it to the smallest valid single line. Everything runs locally in your browser, so sensitive payloads, API keys, and tokens never leave your device.

There is no signup, no rate limit, and no ads cluttering the output. Type or paste on the left, read the result on the right, and copy it with one click.

How to use it

1. Paste your JSON into the input box. It can be minified, messy, or spread across many lines, it does not matter.
2. Pick beautify or minify. Beautify indents and breaks the structure across lines; minify strips all whitespace.
3. Choose an indent of 2 spaces, 4 spaces, or tabs when beautifying, to match your project's style.
4. Check the validity line. A green badge means valid JSON; a red message tells you what the parser tripped on and where.
5. Copy the output and paste it wherever you need it.

Common use cases

• Debugging API responses. Paste a raw response from your network tab and read the structure at a glance.
• Cleaning up config files. Normalize indentation in package manifests, tsconfig files, and CI configs.
• Catching syntax errors. Find the misplaced comma or missing quote that a parser rejects.
• Shrinking payloads. Minify JSON before embedding it in a URL, a data attribute, or an environment variable.
• Code review and documentation. Produce consistently formatted JSON snippets to paste into a PR or a doc.

Strict JSON, nothing else

The validator follows the JSON specification exactly: keys must be double-quoted, no trailing commas, no comments, no single quotes. That strictness is the point. Output that passes here will be accepted by any conformant parser in any language, from Python and Go to a database column or a browser fetch. If you need comments or trailing commas, you are working with JSON5 or JSONC, which are related but separate formats.

Frequently asked questions

Is my JSON uploaded to a server?

No. The formatter runs entirely in your browser with JavaScript. Your JSON is parsed and re-serialized on your own device and never leaves it, so you can safely paste API responses, config files, or anything containing keys and tokens.

What does 'beautify' actually do?

It parses your JSON into a real object and re-prints it with consistent indentation and line breaks, so nested structures are easy to scan. You choose 2 spaces, 4 spaces, or tabs. Beautifying also normalizes the formatting, so messy or single-line JSON becomes readable.

What does 'minify' do?

Minify removes every byte of insignificant whitespace and prints the JSON on a single line. It is the smallest valid representation, which is useful for embedding JSON in a query string, an environment variable, or a payload where size matters.

How does validation work?

The tool runs your text through the same JSON parser browsers use. If it parses, you see a 'Valid JSON' confirmation; if it fails, you get the parser's error message, which usually points at the position of the first problem so you can find the stray comma or unquoted key.

Why does it reject comments and trailing commas?

Strict JSON, the format defined by the JSON specification, does not allow comments or trailing commas. JSON5 and JSONC do, but they are different formats. This tool validates standard JSON so the output is portable everywhere JSON is accepted.

Is there a size limit?

There is no hard limit imposed by the tool, but very large documents (tens of megabytes) depend on your device's memory and the browser's parser. For everyday API responses and config files it is instant.

Does it work offline?

Yes. After the first visit the page is cached, and because all the work happens locally there is no network request when you format or validate.