pyu2f is a python based U2F host library for Linux, Windows, and MacOS. It provides functionality for interacting with a U2F device over USB. pyu2f uses ctypes to make system calls directly to interface with the USB HID device. This means that no platform specific shared libraries need to be compiled for pyu2f to work. By default pyu2f will use its own U2F stack implementation to sign requests. If desired, pyu2f can offload signing to a pluggable command line tool.