PROTOBUFEXPLAINED
PROTOBUF
EXPLAINEDDefine your data and APIs once in a schema, generate consistent code for every language, and evolve them for years without breaking existing clients. This guide takes it apart, byte by byte.
What is Protobuf?
Protocol Buffers (Protobuf) is a schema-driven format for serializing structured data.
- ### A Shared Contract The schema is a single source of truth for your APIs and data. Every team and every language generates code from the same definitions.
- ### Type Safety Shared schemas let generated code catch many shape and type mismatches before data crosses a service boundary.
- ### Compatibility
How it works
"Protobuf" refers to two things: an Interface Definition Language (IDL) for writing schemas, and the encodings those schemas produce. Every message has two possible encodings. One is a compact binary form; the other is a standardized JSON mapping. Both encodings are part of the specification, and either can go over the wire. Code generated from a schema reads and writes both.
JSON writes out a field name for every value, so you can read a JSON payload without the schema. So can any tool that speaks JSON. The binary encoding writes field numbers instead. A decoder with the same schema knows field 2 is `name`, so the bytes never carry the word.
Protobuf filemessage User { int64 id = 1; string name = 2; bool verified = 3;}Dataid: 1042name: "Hiro"verified: true+Protobuf binary11 bytes08 92 08id12 04 48 69 72 6fname18 01verifiedJSON43 bytes{ "id": "1042", "name": "Hiro", "verified": true}Protobuf filemessage User { int64 id = 1; string name = 2; bool verified = 3;}Dataid: 1042name: "Hiro"verified: true+Protobuf binary11 bytes08 92 08id12 04 48 69 72 6fname18 01verifiedJSON43 bytes{ "id": "1042", "name": "Hiro", "verified": true}
The Binary section explains how those bytes are laid out.
From schema to code
You don't write any of the encoding above by hand. A compiler reads the schema and generates native code for each language you target: structs in Go, classes in TypeScript and Java, and so on. The generated code gives you typed constructors, the binary serialization, and the JSON mapping, so a message feels like any other object in your language.