pynxtools-em is a reader plugin for pynxtools (https://github.com/FAIRmat-NFDI/pynxtools) written in Python. It is a tool for reading and translating data from various proprietary and open-source data formats of technology partners from electron microscopy community. The tool standardizes metadata and data such that these are compliant with the NeXus application definition NXem (https://fairmat-nfdi.github.io/nexus_definitions/). pynxtools-em is developed both as a standalone reader and as a tool within NOMAD, an open-source research data management platform for Materials Science (https://nomad-lab.eu/nomad-lab/). The work is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 460197019 (FAIRmat) (https://gepris.dfg.de/gepris/projekt/460197019?language=en).