What is ASUN?
ASUN stands for Array-Schema Unified Notation.
It is a serialization format built around one idea: declare schema once, then send rows as values only.
asun
[{id@int, name@str, active@bool}]:
(1, Alice, true),
(2, Bob, false),
(3, Carol, true)Why It Exists
ASUN is designed for workloads where JSON repeats the same field names over and over:
- LLM prompts and responses
- internal APIs that move repeated records
- caches and storage for structured rows
- logs and exports that are mostly table-shaped
Two Formats
| Format | Best for |
|---|---|
| ASUN text | human-readable exchange, LLMs, APIs |
| ASUN-BIN | internal runtime-to-runtime performance |
Core Properties
- schema and data are separated
- rows are compact and easy to scan
- text can be written with or without scalar hints
- binary encoding is available for runtime-local use
- official libraries share a common spec and compatibility matrix
What to Expect
- significant token and payload savings on repeated rows
- better parsing characteristics than repeated-key JSON
- implementation-specific speedups rather than one universal multiplier
If you need the detailed comparison, continue to Why ASUN over JSON?.