A couple of releases back, I added support for schema registries
to Franz. Some of its users use Protocol Buffers to serialize
their data, so I needed to be able to support that use case. So, I
wrote a parser for the proto2 and proto3 specs and a minimal
serializer/deserializer implementation that doesn't require code
generation on top of that.
You can find the package and docs on the Package server and the source on GitHub.