JSON Formatter & Validator

Prettify, minify, and validate JSON data instantly in your browser. Features auto-repair capabilities for common syntax issues like trailing commas and single quotes, ensuring your configurations remain usable.

JSON (JavaScript Object Notation) is the standard data-interchange format for modern web APIs. It relies on a strict syntax for objects (key-value pairs) and arrays, supporting strings, numbers, booleans, and null values. This tool parses your JSON structure using the browser's native `JSON.parse` engine, and safely reformats it using `JSON.stringify` with consistent indentation (your choice of 2 spaces, 4 spaces, or tabs). It performs basic syntax validation and will alert you if your JSON is fundamentally malformed.

When copying poorly formatted data or raw JavaScript object literals from codebases, strict JSON syntax errors are very common. Valid JSON requires double quotes for all keys and string values, and it strictly forbids trailing commas. The Auto-Repair function attempts a regex-based repair to fix broken JSON by converting single quotes (`'`) to double quotes (`"`) and aggressively stripping out illegal trailing commas right before closing braces (`}` or `]`). However, this is not a complete JSON repair engine; highly corrupted structures or deeply nested invalid characters may still fail to parse.

Note that this tool validates JSON syntax, meaning it ensures the brackets match and the formatting is strictly legal. It does not perform semantic validation or JSON Schema validation against specific external data models. If a key expects a number but receives a string, this tool will consider the JSON perfectly valid as long as the structural syntax is correct.

All parsing, formatting, and minification operations are handled locally. This allows you to safely paste massive database dumps or API responses directly into the formatter to quickly identify nesting errors without transmitting proprietary database information to an external server.