The three I ever use: Cap'n Proto https://capnproto.org/ https://capnproto.org/ Simple Binary Encoding (by Martin Thompson) https://github.com/real-logic/simp

The three I ever use: Cap'n Proto https://capnproto.org/ https://capnproto.org/ Simple Binary Encoding (by Martin Thompson) https://github.com/real-logic/simple-binary-encoding/wiki/Design-Principles https://github.com/real-logic/simple-binary-encoding/wiki/De... and if neither of those will do, raw C-structs on the wire (basically what the other 2 are anyways).