[gsliepen]

Something like MessagePack or CBOR, and if you want versioning, just have a version field at the start. You don't require a schema to pack/unpack, which I personally think is a good thing.

[fmbb]

> You don't require a schema to pack/unpack

Then it hardly solves the same problem Protobuf solves.

[mgaunard]

Arrow is also becoming a good contender, with the extra benefit it is better optimized for data batches.