// the find
crossbario/crossbar
Crossbar.io - WAMP application router
Crossbar.io is a WAMP application router — it handles pub/sub and RPC between distributed services over WebSocket (and raw sockets, MQTT, HTTP bridges). If you've never heard of WAMP, that's the catch: it's a protocol that never broke through, and Crossbar.io lives or dies by it. Aimed at teams who want a single broker for both event-driven messaging and service-to-service calls without bolting together Kafka + gRPC.
The unified RPC + pub/sub model over a single connection is genuinely elegant — you don't need separate infrastructure for calls versus events. Multi-transport support (WebSocket, RawSocket, MQTT, HTTP bridge) means you can onboard IoT devices and browser clients through the same router. The auth story is surprisingly complete: anonymous, ticket, WAMP-CRA, SCRAM, cryptosign, TLS client certs, and dynamic authenticators are all there. Docker images for amd64/armv7/armv8 exist and the config is JSON with a published schema, which makes deployment straightforward.
WAMP has been 'almost mainstream' for over a decade and it isn't — the ecosystem is thin, client libraries are sparse and unevenly maintained outside Python/JS, and you're betting on a protocol with a small community. The README copyright says 2013-2021 and the project has a MODERNIZATION.md, which is a yellow flag that the codebase has been showing its age. The XBR data marketplace layer (blockchain-based data tokenization) is bolted on and reads like scope creep that went nowhere. If you need to talk to anything outside the WAMP world you're immediately writing HTTP bridge glue, which mostly defeats the point of choosing a unified protocol in the first place.