This is a bit lower level as it's only concerned with serializing, but a package I wrote called json_syntax[1] will take @dataclass or @attr.s classes decorated

This is a bit lower level as it's only concerned with serializing, but a package I wrote called json_syntax[1] will take @dataclass or @attr.s classes decorated with type annotations and build encoders and decoders for them. It also handles Union types reasonably well and lets you put in hooks to handle ugly cases. It's used in production on a system with a big complicated payload, and I designed it to be easily extensible if the standard rules don't work for you. [1]: https://pypi.org/project/json-syntax/ https://pypi.org/project/json-syntax/