MessagePack
MessagePack is a practical middle ground when JSON is too large and Protobuf is too rigid. Know tag-byte structure for debugging wire captures.
What It Defines
Binary JSON-like serialization: compact type tags prefix values (nil, bool, int, float, str, bin, array, map, ext). Schema-less like JSON/CBOR; popular in Redis, RPC, and game networking for smaller payloads than JSON.
Canonical (Normative)
Convenient (Practical)
The primary standards body for internet protocols. Produces RFCs through working groups. Use IETF Datatracker for active drafts, working group status, and revision history.
Related Specs
CBOR is the binary envelope behind COSE cryptographic messages and many constrained-device protocols. Typed length-prefixed encoding without a schema — unlike Protobuf.
JSON is the lingua franca of web APIs. RFC 8259 is short and worth reading once — it clarifies edge cases around numbers, encoding, and trailing commas.
Protobuf is the wire format for gRPC and many high-performance internal APIs. Schemas are also used for event/message contracts in Kafka/pubsub systems.