> they have very many formats implemented It's not "they", it's whoever wants to implement serde support for their own thing, can do it (so, many 3rd party cra

> they have very many formats implemented It's not "they", it's whoever wants to implement serde support for their own thing, can do it (so, many 3rd party crates have a "serde" feature that can be toggled on/off). > Which format is zero penalty This one is tough to answer unless you provide details re: what's your in-process data format, what's your target serialization format and whether it's binary or not, what's the objective function (serialization speed, deserialization speed, storage efficiency), and what exactly you mean by 'zero penalty' (which penalty?). // note that there's also alternative frameworks worth mentioning like rkyv and borsh-rs, each optimizing their own objective function