The rootfilespec package is designed to efficiently parse ROOT file binary data into python datastructures. It does not drive I/O and expects materialized bytes buffers as input. It also does not return any types beyond python dataclasses of primitive types (and numpy arrays thereof). The goal of the project is to provide a stable and feature-complete read/write backend for packages such as uproot.
Further details on the design decisions can be found in docs/design.md.