MsgPack

MsgPack, short for MessagePack, is a binary serialization format designed to be compact and fast. It provides a binary encoding for data structures commonly used in JSON-like data, including integers, floats, strings, binary blobs, booleans, nil, arrays, maps, and extension types for user-defined data. The goal is to deliver small message sizes with efficient parsing and minimal overhead, making it well suited for network transmission and storage.

The format uses a concise set of type prefixes that encode both the data type and its length, enabling compact representations for small values and scalable encoding for larger ones. Data types include nil, booleans, integers (signed), floating point numbers, strings (UTF-8), binary data, arrays, maps, and extension types (ext) that allow custom or application-specific payloads. MessagePack is designed to be independent of programming language and platform, with a broad ecosystem of libraries that implement the specification.

MessagePack is schema-less; it does not require a predefined schema to serialize or deserialize data. Instead, a program maps its native data structures to the corresponding MessagePack types. This makes it flexible for heterogeneous data and dynamic languages, while also placing some burden on developers for versioning and compatibility when evolving data formats. It is commonly used in remote procedure calls, data streaming, and compact storage where JSON might be too verbose.

The format is widely supported across languages and platforms, with numerous libraries and tooling available. Its main advantages are smaller payload sizes and faster parsing relative to JSON, at the cost of human readability and more complex debugging. See also JSON, Protobuf, and BSON for alternative binary or text-centric serialization approaches.