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.

Purpose

To provide strongly typed, compact, and efficient cross-language data exchange, with schemas guaranteeing compatibility.

Mechanism

A .proto IDL defines message types with field numbers. When encoding, each field starts with a (field_number<<3 | wire_type) tag; integers use varint, and strings and nested messages use length prefixes. Unknown fields stay forward-compatible. proto3 simplifies the syntax.

Use cases

gRPC transport protocol
Google internal data storage
Mobile APIs (saving bandwidth)
Configuration and persistence

Examples

Input

message User { string name = 1; }

Output

Binary encoding

Requires protoc compilation

Common errors

Changing field numbers breaks compatibility: Once assigned, numbers must not be reused or changed

Related terms

Avro is a row-oriented binary serialization format from the Hadoop ecosystem; its schema is embedded or external, and it is used for big data storage and Kafka.

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

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

Related tools

Protobuf Decode

Protobuf Decode — pure client-side tool. Privacy-first, no server round-trip.

References