MessagePack is a binary data serialisation format that encodes structured data compactly while preserving a data model compatible with JSON, allowing maps, arrays, strings, integers, and floats to be transmitted in far fewer bytes than their textual equivalents. It uses a type-prefixed encoding that minimises overhead, making it well-suited to high-throughput messaging, caching, and inter-service communication. MessagePack trades human readability for speed and compactness, sitting between verbose JSON and schema-bound formats like Protocol Buffers.
Overview
- MessagePack was created to make JSON-shaped data dramatically smaller and faster to parse for systems that exchange large volumes of messages. It keeps the same flexible, schema-free data model so existing JSON structures map directly onto its binary form.
- Each value is prefixed by a type byte that may also encode a small immediate value or length, so short strings and small integers occupy as little as one byte. This yields substantial bandwidth and CPU savings in messaging, caching, and RPC paths.
Key aspects
- A type-prefix scheme distinguishes integers, strings, arrays, maps, and extensions compactly.
- Schema-free encoding preserves JSON compatibility without an external definition file.
- Extension types allow application-specific binary payloads to be tagged.
- Streaming-friendly framing supports incremental encode and decode.
Applications
- High-throughput Message Queue and pub/sub systems reducing payload size.
- In-memory caches and key-value stores serialising structured values.
- Inter-service RPC where JSON overhead is prohibitive.
- Constrained Internet of Things and Embedded Systems communication.