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Format, validate, beautify and minify JSON data instantly. Detects syntax errors and shows them clearly. Perfect for developers and API testing.
Paste your JSON and click the button to process.
JSON (JavaScript Object Notation) is the most common data format used on the web. It's human-readable, language-independent and used by virtually every API, config file and modern application. A valid JSON document contains objects {}, arrays [], strings, numbers, booleans and null.
.json file.true/false❌ Invalid JSON:
{
name: 'John', // no quotes on key, single quotes
age: 30,
city: 'New York', // trailing comma
}✅ Valid JSON:
{
"name": "John",
"age": 30,
"city": "New York"
}All processing happens instantly in your browser. Your JSON is never sent to any server and never stored. Safe for confidential data.
Beautify (or 'pretty print') adds indentation and line breaks to make JSON easy to read. Minify does the opposite: it removes all whitespace so the JSON takes as little space as possible — ideal for network transmission and production APIs.
This error usually means invalid syntax: a missing comma, extra comma, unquoted key, single quotes instead of double quotes, or a stray character. The validator will show you the line and position where the problem starts — check just before that spot.
Yes! Since processing happens locally in your browser, there's no upload limit. Files with tens of thousands of lines are handled instantly. Very large files (100MB+) may briefly freeze your browser tab while formatting.
No. Standard JSON does not support comments (unlike JavaScript). If you need comments, use JSON5 or JSONC — but those aren't accepted by most parsers. This tool follows the strict JSON spec.
JSON requires double quotes (") around all strings and keys. Single quotes ('), even though valid in JavaScript, are not valid in JSON. Replace all single quotes with double quotes to fix this.
Yes! Everything happens in your browser using JavaScript's built-in JSON parser. Nothing is uploaded, logged or stored anywhere. Safe for API keys, tokens and confidential data.