Biniou (pronounced "be new") is a binary data format designed for speed, safety, ease of use and backward compatibility as protocols evolve. Biniou is vastly equivalent to JSON in terms of functionality but allows implementations several times faster (4 times faster than yojson), with 25-35% space savings.

Biniou data can be decoded into human-readable form without knowledge of type definitions except for field and variant names which are represented by 31-bit hashes. A program named bdump is provided for routine visualization of biniou data files.

The program atdgen is used to derive OCaml-Biniou serializers and deserializers from type definitions.

Biniou format specification: biniou-format.txt