mldtypes is a stand-alone implementation of several NumPy dtype extensions used in machine learning libraries, including: bfloat16: an alternative to the standard float16 format float8*: several experimental 8-bit floating point representations including: float8e4m3b11fnuz, float8e4m3fn, float8e4m3fnuz, float8e5m2, float8_e5m2fnuz int4 and uint4: low precision integer types.