MessagePack

MessagePack is an efficient binary serialization format, similar to JSON but more compact, with multilingual support, used for RPC and caching.

Purpose

To provide serialization that is smaller and faster than JSON for high-performance RPC and caching.

Mechanism

A single-byte type marker distinguishes nil, bool, integers, floats, strings, byte arrays, arrays, and maps. Small positive/negative integers use one-byte fixint; short strings use fixstr. It is not self-describing (a schema or convention is needed) but more compact than JSON.

Use cases

Redis serialized values
Thrift/MsgPack RPC
Game server communication
Embedded data exchange

Examples

Input
```
{"a":1}
```
Output
```
81 a1 61 01
```
A map with one pair

Common errors

The lack of a schema causes cross-language type mismatches: Use an IDL or explicit type conventions

Related terms

CBOR (Concise Binary Object Representation) is a binary form of JSON, standardized in RFC 8949, more compact and supporting more data types.

JSON (JavaScript Object Notation) is a lightweight data interchange format based on JavaScript object literals, using key-value pairs and arrays.

Protocol Buffers

Protocol Buffers is Google's language-neutral binary serialization format; it requires a .proto schema definition and is more compact and type-safe than JSON/XML.

Related tools

MessagePack Decode

MessagePack Decode — pure client-side tool. Decodes real MessagePack binary (hex or base64 input, auto-detected) to pretty JSON. Full official spec: fixints, str/bin/array/map (fix + 8/16/32), ext (fixext1-16, ext8/16/32), float32/64, uint/int 8-64. Privacy-first, no server round-trip.

MessagePack Encode

MessagePack Encode — pure client-side tool. Encodes JSON to real MessagePack binary, wire-compatible (aligned with msgpack-python defaults): shortest integer forms, str/bin/array/map families, extension types via $ext. Map keys keep insertion order. Output hex (default) or base64. Privacy-first, no server round-trip.

References