JSON Formatter & Validator

What is JSON?

JSON is a lightweight, text-based data interchange format derived from JavaScript object syntax, defined by RFC 8259. It is language-independent and supported natively by every modern programming language.

JSON is used everywhere: REST API responses, configuration files (package.json, tsconfig.json), database documents (MongoDB, Firestore), cloud function payloads, webhooks, and much more.

{
  "name": "Alice",
  "age": 30,
  "isAdmin": false,
  "scores": [95, 87, 100],
  "address": {
    "city": "London",
    "zip": "EC1A 1BB"
  }
}

JSON Syntax Rules

JSON has six data types and a strict syntax. Understanding these rules prevents the most common parsing errors.

• OObjects — key/value pairs wrapped in { }. Keys must be double-quoted strings. Pairs separated by commas. No trailing comma allowed.
• AArrays — ordered lists wrapped in [ ]. Elements can be any JSON value. No trailing comma allowed.
• SStrings — must use double quotes only. Supports Unicode. Escape special chars: \"\\\n\t.
• NNumbers — integers and floats. No leading zeros (except 0.5). No hex, octal, or NaN/ Infinity.
• BBooleans — true and false — lowercase only.
• ∅Null — null — lowercase only. Represents the absence of a value.

Common JSON Errors & How to Fix Them

Our Auto-Fix feature handles most of these automatically. Here's what to watch for:

{ "a": 1, "b": 2, }

{ "a": 1, "b": 2 }

{ 'name': 'Alice' }

{ "name": "Alice" }

{ name: "Alice" }

{ "name": "Alice" }

{ "a": 1 "b": 2 }

{ "a": 1, "b": 2 }