JSON (JavaScript Object Notation) is the de-facto data interchange format for APIs, config files, and web services. Raw JSON from APIs is often minified — no whitespace, hard to read. This formatter beautifies JSON with proper indentation and syntax highlighting, and validates it at the same time, reporting the exact line and character of any syntax error.
Everything runs in your browser using the native JSON.parse() engine. No data is ever sent to a server. Supports JSON objects, arrays, strings, numbers, booleans, and null values.
How to format and validate JSON
1. Paste your JSON into the input field. 2. Click Beautify to format with 2-space indentation, or Minify to remove all whitespace. 3. If there's a syntax error, the tool highlights the exact position and explains the problem. 4. Click Copy to copy the formatted output.
Common JSON syntax rules
Keys must be in double quotes (not single quotes). No trailing commas after the last item in an array or object. Strings must escape special characters: use \n for newline, \\ for backslash, \" for quotes. Numbers, booleans (true/false), null, arrays, and objects are all valid JSON values. The root element can be an object, array, string, number, or boolean.
What causes 'Invalid JSON' errors?
Common causes: trailing commas after the last item, single quotes instead of double quotes, unquoted property keys, and JavaScript-specific values like undefined or NaN which are not valid JSON.
What's the difference between Beautify and Minify?
Beautify adds indentation and line breaks for readability — use this when debugging APIs or reading config files. Minify removes all whitespace to reduce file size — use this for production JSON payloads.
Is this JSON formatter safe for sensitive data?
Yes. All processing happens entirely in your browser using JavaScript. Your JSON is never sent to any server.
How do I find the exact line causing a JSON error?
This tool highlights the exact position of syntax errors. Common issues: trailing commas after the last item in an object or array (not allowed in JSON), single quotes instead of double quotes, unescaped special characters in strings, and missing commas between key-value pairs.
What's the difference between JSON and JSON5?
JSON5 is a superset of JSON that allows comments, trailing commas, single quotes, and unquoted keys. It's human-friendly for config files but not supported by standard JSON parsers. Most APIs use strict JSON. If you're editing a config file like .eslintrc or tsconfig, it may accept JSON5 or JSONC (JSON with Comments).
Is it safe to paste sensitive JSON data here?
Yes — this tool processes everything 100% in your browser. Your JSON data never leaves your device and is not sent to any server. You can verify this by disconnecting from the internet and testing — it works completely offline. There are no analytics on the content you paste.
What is JSON minification used for?
Minified JSON removes all whitespace and newlines, reducing file size by 20–40%. This is useful for API responses (smaller payload = faster transfer), storing JSON in databases (less storage), and embedding JSON in source code. Never commit minified JSON to version control — use beautified JSON for readability.