gRPC in the browser without grpc-web: the wire protocol over a WebRTC DataChannel

John Davis — Sun, 01 Nov 2026 17:22:26 +0000

grpc-web exists because browsers can't speak HTTP/2 trailers.
The usual answer is a translation proxy in front of your service.
We took a different one: run the actual gRPC wire protocol —
length-prefixed frames, HPACK-free, all four call shapes — over a
single WebRTC RTCDataChannel, and generate the runtime for it
from your .proto.

grpc-over-datachannels is that experiment, grown up:

Dependency-free generated runtimes for 16 languages — JavaScript/TypeScript, Go, Rust, Python, Ruby, PHP, Lua, C, C++, Dart, Java, Kotlin, Scala, Swift, C#, and Zig. Browser and native. The generated code is stdlib-only; there is no grpc library underneath it.
Our own WebRTC stack. ICE, DTLS, and SCTP written from scratch, so the native clients don't depend on a WebRTC library either.
Graded against stock gRPC. The generated implementations are tested against the reference implementations through a TCP↔DataChannel proxy — the oracle is the real thing, not a reimplementation of it.
WebRTC-Direct. A server prints one certhash multiaddr; a client dials it. No signaling server. Direct on a LAN, through a TURN relay behind symmetric NAT, or full ICE with STUN in peer mode — with runnable examples in every language.
A Kafka proxy in Rust. grpcdc.kafka.v1.Kafka exposes Apache Kafka as a generated gRPC service, so any generated client — including a browser tab — can produce and consume without a Kafka client library. The same generated e2e suite runs against Kafka and Redpanda in CI.

If you only have thirty seconds, the whole pitch is a 2-minute
video: https://youtu.be/LwrXpnlMlgA — and the Kafka proxy gets
its own: https://youtu.be/KJ98a4ApZ4E

The part we're proudest of is also the strangest: almost
everything in the repos is generated. The runtimes, the tests,
the examples, and the docs come from recursive generators, so
sixteen languages can't quietly drift apart. When a language
misbehaves, we fix the generator, not sixteen codebases.

Try it without installing anything — the stub generator runs in
your browser: https://browser-grpc.github.io/grpc-over-datachannels/app/

Code, releases (npm / PyPI / NuGet / GHCR / GitHub-hosted Maven):
https://github.com/browser-grpc/grpc-over-datachannels

Longer write-ups, with the design trade-offs:

Questions and hostile edge cases welcome — the NAT and framing ones especially.

DEV Community: John Davis

gRPC in the browser without grpc-web: the wire protocol over a WebRTC DataChannel