Project Title

toon — Compact, human-readable, schema-aware JSON for LLM prompts

Overview

Token-Oriented Object Notation (TOON) is a serialization format designed to pass structured data to Large Language Models (LLMs) with reduced token usage. It combines the best of YAML and CSV, offering a compact, human-readable format that is optimized for LLM input, making it an efficient choice for uniform arrays of objects.

Key Features

Token-efficient: Typically 30-60% fewer tokens on large uniform arrays vs formatted JSON
LLM-friendly guardrails: Explicit lengths and fields enable validation
Minimal syntax: Removes redundant punctuation for a cleaner look

Use Cases

Data Input for LLMs: Use TOON to pass structured data to Large Language Models with reduced token usage.
Uniform Data Representation: Ideal for uniform arrays of objects where JSON verbosity is a concern.
Schema-aware Data Handling: Useful in applications requiring explicit structure and validation for reliable data parsing.

Advantages

Compactness: Achieves CSV-like compactness with explicit structure for LLM reliability.
Human-Readable: Retains readability while being optimized for token efficiency.
Schema-Aware: Helps LLMs parse and validate data more reliably.

Limitations / Considerations

Not Ideal for Deeply Nested Data: JSON may be more efficient for deeply nested or non-uniform data structures.
Learning Curve: Developers unfamiliar with TOON's syntax may need to invest time in learning the format.

JSON: A standard data interchange format that TOON aims to optimize for LLMs.
YAML: A human-readable data serialization standard that TOON draws inspiration from.
CSV: A simple, widely-used format for tabular data that TOON aims to improve upon for LLM contexts.

Basic Information

GitHub: https://github.com/toon-format/toon
Stars: 14,060
License: MIT
Last Commit: 2025-11-13

📊 Project Information

Project Name: toon
GitHub URL: https://github.com/toon-format/toon
Programming Language: TypeScript
⭐ Stars: 14,060
🍴 Forks: 546
📅 Created: 2025-10-22
🔄 Last Updated: 2025-11-13

🏷️ Project Topics

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