XRDlicious is an online computational tool for calculating powder X-ray diffraction and neutron diffraction patterns (diffractograms) and partial and total radial distribution functions [(P)RDFs] from crystal structures. It features a user-friendly browser-based interface that supports widely used structural file formats, such as CIF, POSCAR, XYZ and LMP. The structures can be either uploaded or retrieved directly from the Crystallography Open Database, Materials Project and Automatic FLOW databases via an integrated search interface. Uploaded structures can be modified and exported in CIF, POSCAR, LMP or XYZ formats. The tool also enables the conversion of experimental powder diffraction data between different wavelengths, to d-space or q-space representations, and between fixed or automatic divergence slits. By eliminating the need for software installation, this application ensures accessibility across various devices (including mobile phones and tablets) and different computer operating systems. Its ability to simultaneously plot diffraction patterns from multiple structures is particularly useful for comparing structures obtained from computational simulations. Beyond research applications, its intuitive interface also makes it suitable for educational purposes, allowing students to explore concepts such as diffraction patterns and (P)RDFs in an easily approachable way. XRDlicious is accessible at https://xrdlicious.com.