JSON Formatter & Validator — Free Online Tool

JSON Formatting Example: Before & After

Here is what our JSON formatter does. The minified JSON on the left is hard to read. The formatted version on the right has proper indentation, line breaks, and structure — making it easy to scan and debug.

{"users":[{"id":1,"name":"Alice",
"email":"[email protected]",
"roles":["admin","editor"],
"active":true},{"id":2,
"name":"Bob","email":
"[email protected]","roles":
["viewer"],"active":false}],
"meta":{"total":2,"page":1}}

{
  "users": [
    {
      "id": 1,
      "name": "Alice",
      "email": "[email protected]",
      "roles": ["admin", "editor"],
      "active": true
    },
    {
      "id": 2,
      "name": "Bob",
      "email": "[email protected]",
      "roles": ["viewer"],
      "active": false
    }
  ],
  "meta": {
    "total": 2,
    "page": 1
  }
}

What Is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data format used to exchange information between servers, APIs, and web applications. Created by Douglas Crockford in the early 2000s, JSON has replaced XML as the dominant data interchange format on the web.

Almost every modern API — from Google Analytics to GitHub — returns data in JSON format. Configuration files (package.json, tsconfig.json), databases like MongoDB, and tools like Postman all use JSON daily.

A JSON document is built from two structures:

• Objects — unordered sets of key-value pairs wrapped in { }
• Arrays — ordered lists of values wrapped in [ ]

JSON Data Types

JSON supports exactly six data types. Understanding them is key to writing and debugging valid JSON:

For the full specification, see the official json.org documentation or RFC 8259.

How to Format JSON Online

Our JSON beautifier processes everything in your browser — no data is sent to any server. Here is how to use it:

JSON Formatter Features

This free online JSON formatter and validator includes everything you need:

JSON vs XML: Which Format Is Better?

Before JSON became the standard, XML was the dominant data interchange format. Here is how they compare:

For most modern web development, JSON is the better choice due to its smaller size, native JavaScript support, and simpler syntax. XML still has advantages for document-centric use cases and where schemas are required. Read more on MDN’s JSON documentation.

Common JSON Errors and How to Fix Them

If the JSON validator shows an error, it is usually one of these mistakes. Our Repair button can auto-fix the first three:

For errors that cannot be auto-repaired, the JSON checker shows the exact line number so you can locate and fix the issue manually.

JSON Syntax Rules

Valid JSON must follow these rules defined in RFC 8259:

Frequently Asked Questions