JSON Formatter & Validator

Format, validate, and beautify JSON online. Instantly detect syntax errors and pretty-print JSON data.

Input JSON

Output

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write, and easy for machines to parse and generate.

How to use this tool

Paste your JSON into the input field
Click Format to pretty-print with proper indentation
Errors are highlighted inline if the JSON is invalid

JSON syntax rules

Keys must be strings wrapped in double quotes
Values can be strings, numbers, booleans, arrays, objects, or null
No trailing commas allowed
No comments allowed in standard JSON

Example

Input: {"name":"Alice","age":30,"active":true}

Formatted output:

{
  "name": "Alice",
  "age": 30,
  "active": true
}

FAQs

Is my data sent to a server? No. All processing happens in your browser. Nothing is transmitted.

What is the maximum JSON size? Limited only by your browser memory. Works well up to several MB.

Why is my JSON invalid? Common causes: trailing commas, single-quoted strings, unescaped characters, or missing brackets.