My MessagePack implementation is designed for embedded: https://github.com/ludocode/mpack https://github.com/ludocode/mpack It can be built to a very small co

My MessagePack implementation is designed for embedded: https://github.com/ludocode/mpack https://github.com/ludocode/mpack It can be built to a very small code size, especially when you disable libc, allocations, etc. There are some people using it on embedded devices like Arduino. There's someone working on a port to 8-bit microcontrollers that don't have a 64-bit float, so you may want to look into that as well; see the open issue for it on the GitHub link above.