JSON Formatter & Validator

Paste JSON to format it, validate syntax, minify, or sort keys. Works instantly in your browser.

Input JSON

Output

Quick Answer

Paste your JSON into the input box and click Format. The formatter uses the browser's built-in JSON parser to validate the syntax, then outputs it with consistent indentation. Any errors — trailing commas, single quotes, missing brackets — are flagged with the exact line number.

About this JSON formatter

This tool formats (pretty-prints) JSON, validates syntax, minifies (compresses), and optionally sorts keys alphabetically. Everything runs in your browser — your data is never sent to a server.

Formatting vs. minifying

Formatting adds indentation and line breaks to make JSON human-readable. Minifying removes all whitespace to reduce file size — useful when transmitting JSON over a network where every byte counts. Use the indent selector to control how many spaces are used for indentation.

Why validate JSON?

Invalid JSON causes parsing errors in code. Common mistakes include trailing commas (not allowed in JSON), single quotes instead of double quotes, unquoted keys, and comments. This validator uses the browser's built-in JSON parser — if it passes here, it's valid JSON per the spec.

Sorting keys

Sorting object keys alphabetically makes JSON easier to scan and compare. It's useful for diffing config files or API responses where key order varies between versions. Note: JSON objects are technically unordered, but sorted output is more consistent for human review.

Frequently asked questions

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data format for storing and exchanging structured data. It uses key-value pairs and arrays, and is the standard format for web APIs and config files.

What are common JSON errors?

The most common JSON errors are trailing commas after the last item in an object or array, single quotes instead of double quotes around strings and keys, unquoted keys, and JavaScript comments (// or /* */) which are not valid in JSON.

What is the difference between formatting and minifying JSON?

Formatting (prettifying) adds indentation and line breaks to make JSON human-readable. Minifying removes all unnecessary whitespace to reduce file size for transmission. Both represent the same data. Use formatted JSON when debugging, minified JSON in production API responses.

Is this JSON formatter safe to use with sensitive data?

All formatting, validation, and minification happens in your browser using JavaScript. No data is sent to any server. That said, avoid pasting production credentials, API keys, or personally identifiable information into any online tool as a general practice.