What is JSON5?

JSON5 is an extension of JSON that aims to be easier to write and maintain by hand. It's not a replacement for JSON but rather a superset that allows for a more relaxed, human-friendly syntax while remaining fully compatible with JavaScript object literals.

JSON5 Features

💬 Comments

// Single-line comment
/* Multi-line
   comment */

🔑 Unquoted Keys

{
  name: "value",
  $price: 99,
  _private: true
}

✂️ Trailing Commas

{
  "items": [
    "one",
    "two",
    "three",  // OK!
  ],
}

🔤 Single Quotes

{
  'single': 'quotes',
  "mixed": 'allowed'
}

🔢 Special Numbers

{
  hex: 0xDEADBEEF,
  infinity: Infinity,
  negInfinity: -Infinity,
  nan: NaN,
  leadingDot: .5,
  trailingDot: 5.
}

📝 Multi-line Strings

{
  multiline: "Line 1\
Line 2\
Line 3"
}

JSON5 vs JSON vs JSONC

Feature	JSON	JSONC	JSON5
Comments	❌	✅	✅
Trailing commas	❌	✅	✅
Unquoted keys	❌	❌	✅
Single quotes	❌	❌	✅
Hex numbers	❌	❌	✅
Infinity/NaN	❌	❌	✅
Multi-line strings	❌	❌	✅
Leading/trailing decimals	❌	❌	✅

Common Use Cases

Configuration files — Human-readable config with comments for documentation
Data fixtures — Test data that's easy to maintain and modify
API mocking — Quick prototyping with relaxed syntax
Build tool configs — Babel, webpack, and other tools support JSON5

Related Tools

📝 JSONC → JSON

Strip comments from JSONC files.

✨ JSON Formatter

Format and validate standard JSON.

🔧 Fix JSON

Auto-repair broken JSON syntax.

📄 JSON5 Formatter & Validator