This document introduces h5web, a web-based viewer for HDF5 files developed by Loïc Huder at the European Synchrotron Radiation Facility. HDF5 has become the standard format for data acquired at ESRF. H5web allows users to browse HDF5 file hierarchies, inspect metadata and attributes, and display n-dimensional datasets with interactive visualizations. Built with React and available as open-source, h5web demonstrates browsing and visualizing capabilities through a demo. Future work includes incorporating NeXus support and deploying the visualization components in other applications.