JSON ↔ TOON Converter

Convert between JSON and Token-Oriented Object Notation. Reduce LLM token costs by 30-60%.

~0 tokens
~0 tokens

30-60% Token Savings

TOON format dramatically reduces token count by eliminating redundant JSON syntax. Perfect for large datasets sent to LLMs, saving you significant API costs on every request.

Optimized for Tabular Data

TOON excels at uniform arrays of objects. Instead of repeating field names in every object, TOON declares them once and streams values in a clean, CSV-like format.

LLM-Friendly Format

Designed specifically for Large Language Model prompts. TOON's human-readable structure helps LLMs parse data more accurately while using fewer tokens than JSON or YAML.

What is TOON (Token-Oriented Object Notation)?

TOON is a compact, human-readable serialization format specifically designed for passing structured data to Large Language Models with significantly reduced token usage. It's a lossless, drop-in representation of JSON data that can save you 30-60% in token costs.

Why Use TOON?

LLM tokens cost money, and standard JSON is verbose. When you're making hundreds or thousands of API calls with uniform tabular data, eliminating repeated keys compounds into massive savings. TOON is your translation layer: use JSON programmatically, convert to TOON for LLM input.

Key Features

  • Token-Efficient: Typically uses 30-60% fewer tokens than JSON
  • Human-Readable: Clean, intuitive syntax similar to YAML and CSV
  • Tabular Format: Declare keys once, stream data as rows for uniform arrays
  • LLM-Friendly: Explicit length markers help LLMs validate and track structure
  • Minimal Syntax: Removes redundant punctuation like braces and brackets

When to Use TOON

TOON shines for:

  • Uniform arrays of objects with identical fields (the sweet spot)
  • Large datasets sent to LLMs (100+ records)
  • Repeated LLM API calls where token costs matter
  • Analytics data, user records, product catalogs, and similar structured data

For deeply nested or non-uniform data, JSON may actually be more efficient. TOON is a specialized tool for specific use cases, not a universal JSON replacement.

Example Comparison

Here's how TOON reduces tokens for a simple user list:

JSON (257 tokens):

{
  "users": [
    { "id": 1, "name": "Alice", "role": "admin" },
    { "id": 2, "name": "Bob", "role": "user" }
  ]
}

TOON (166 tokens - 35% savings):

users[2]{id,name,role}:
1,Alice,admin
2,Bob,user

Try our converter above to see real token savings on your own data. The savings scale dramatically with larger datasets!