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TOON to JSON Converter

TOON (Token-Oriented Object Notation) is a compact, human-readable, schema-aware JSON format designed for LLM prompts. This tool helps you convert between TOON format and JSON format bidirectionally.

All operations are completed locally in your browser, we do not save any of your information, protecting your privacy.

What is TOON?

TOON is a compact data format specifically designed for LLM (Large Language Model) prompts. It is more token-efficient than JSON while maintaining human readability. TOON is particularly suitable for handling uniform arrays of objects (objects with the same fields and primitive values).

Main features of TOON format:

• Compactness: More token-efficient than JSON
• Readability: Human-readable format
• Structured: Supports array length and field header declarations
• Deterministic: Clear quoting rules, reducing parsing errors

TOON Example

users[3]{id,name,role,lastLogin}:
  1,Alice,admin,2025-01-15T10:30:00Z
  2,Bob,user,2025-01-14T15:22:00Z
  3,Charlie,user,2025-01-13T09:45:00Z

Corresponding JSON format:

{
  "users": [
    { "id": 1, "name": "Alice", "role": "admin", "lastLogin": "2025-01-15T10:30:00Z" },
    { "id": 2, "name": "Bob", "role": "user", "lastLogin": "2025-01-14T15:22:00Z" },
    { "id": 3, "name": "Charlie", "role": "user", "lastLogin": "2025-01-13T09:45:00Z" }
  ]
}