Show HN: ISON – Data format that uses 30-70% fewer tokens than JSON for LLMs

ISON (Interchange Simple Object Notation) - a data format optimized for LLMs and Agentic AI.

The problem: JSON wastes tokens. Curly braces, quotes, colons, commas - all eat into your context window.

ISON uses tabular patterns that LLMs already understand from training data:

JSON (87 tokens): { "users": [ {"id": 1, "name": "Alice", "email": "[email protected]"}, {"id": 2, "name": "Bob", "email": "[email protected]"} ] }

ISON (34 tokens): table.users id:int name:string email 1 Alice [email protected] 2 Bob [email protected]

Features: - 30-70% token reduction - Type annotations - References between tables - Schema validation (ISONantic) - Streaming format (ISONL)

Implementations: Python, JavaScript, TypeScript, Rust, C++ 9 packages, 171+ tests passing

pip install ison-py # Parser pip install isonantic # Validation & schemas

npm install ison-parser # JavaScript npm install ison-ts # TypeScript with full types npm install isonantic-ts # Validation & schemas

[dependencies] ison-rs = "1.0" isonantic-rs = "1.0" # Validation & schemas

Looking for feedback on the format design.