TOON Format Converter
Convert between JSON, YAML, and TOON (Token-Oriented Object Notation). TOON uses ~40% fewer tokens for LLM inputs while maintaining better accuracy.
How it works
💡 TOON is perfect for sending structured data to LLMs - it's more compact and more accurate!
Input
Output
40% Fewer Tokens
TOON reduces token usage by ~40% compared to JSON, saving API costs for LLM applications.
Better Accuracy
73.9% parsing accuracy vs JSON's 69.7% across multiple LLM models in benchmarks.
Bidirectional
Convert freely between JSON, YAML, and TOON formats with lossless round-trips.
Lightning Fast
Client-side processing with instant conversions. Your data never leaves your browser.
What is TOON?
TOON (Token-Oriented Object Notation) is a compact, human-readable encoding format designed specifically for LLM input. It represents the same JSON data model but uses significantly fewer tokens.
While developers work with JSON programmatically, TOON serves as an optimization layer when sending data to language models, where token consumption directly impacts API costs.
JSON Example
[ {"name": "Alice", "age": 30}, {"name": "Bob", "age": 25} ]TOON Equivalent
[2] {name,age} Alice 30 Bob 25Key Features
- •YAML-like indentation for nested objects and simple structures
- •CSV-style tables for uniform arrays of objects (TOON's sweet spot)
- •Explicit structure with array length declarations
[N]and field headers{field1,field2} - •Reduced syntax with minimal quoting and no braces for objects
When to Use TOON
LLM Prompts
Reduce token costs when sending structured data to GPT, Claude, or other LLMs in your applications.
Tabular Data
Perfect for uniform arrays of objects like user lists, product catalogs, or database query results.
Cost Optimization
Save 30-60% on API costs for applications making frequent LLM calls with data-heavy prompts.