Show HN: ISON – Data format that uses 30-70% fewer tokens than JSON for LLMs https://bit.ly/4qnahWt

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": "alice@example.com"}, {"id": 2, "name": "Bob", "email": "bob@example.com"} ] } ISON (34 tokens): table.users id:int name:string email 1 Alice alice@example.com 2 Bob bob@example.com 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. https://bit.ly/4qxYQvr December 27, 2025 at 12:38AM