protoc-go

Warning — experimental and under active development. Not ready for production use; APIs may change without notice.

A pure Go implementation of the Protocol Buffers compiler (protoc). Use it as a CLI drop-in replacement, or embed it as a library directly in your Go program — no protoc binary, no subprocess.

protoc-go is the compiler behind Kaja. Kaja needed a pure-Go protoc so it could embed the compiler directly into its binary — which also made it much easier to pass Apple App Store review.

CLI

go install github.com/wham/protoc-go/cmd/protoc-go@latest

protoc-go --go_out=. --go_opt=paths=source_relative -I./protos api/v1/service.proto

The standard protoc flags work (--proto_path, --descriptor_set_out, --decode, --encode, plugins, …). See the protoc reference for the full list.

Library

Compile .proto files programmatically and run code-gen plugins:

import "github.com/wham/protoc-go/protoc"

c := protoc.New(protoc.WithProtoPaths("./protos"))

result, err := c.Compile("api/v1/service.proto")
if err != nil {
    log.Fatal(err)
}

files, _ := result.RunPlugin("protoc-gen-go", "paths=source_relative")
for _, f := range files {
    os.WriteFile(f.Name, []byte(f.Content), 0644)
}

You can also:

• compile in-memory sources with protoc.WithOverlay(map[string]string{...}),
• serialize a FileDescriptorSet via result.AsFileDescriptorSet(),
• run Go plugins in-process (no subprocess) with result.RunLibraryPlugin — they receive the same CodeGeneratorRequest a subprocess plugin would.

Compiler is safe for concurrent use: create one and reuse it across goroutines.

Build & test

scripts/test            # compare Go protoc-go output against C++ protoc
scripts/bench           # performance comparison

Requires Go 1.23+, plus a C++ protoc on your PATH for the comparison suites (e.g. brew install protobuf).

See AGENTS.md for the architecture, how the test/bench harnesses work, and the automated development loop.