Salt caverns have been used as hydrogen (H2) storage solutions in four locations worldwide with refineries and the petrochemical industry relying on these supplies as strategic back-up. The viability of storing H2 within salt caverns is advantageous given their large volumetric capacities, their flexible operation with large injection and withdrawal rates, and for being a proven technology for the underground storage of a wide variety of gases and liquids. However, to our knowledge, there are no open-source web-based software tools to assess the technical potential of salt caverns for H2 storage. This work aims to fill that gap by introducing the GeoH2 Salt Storage and Cycling App, a computer program that models H2 storage capacities, and injection/withdrawal cycles in salt caverns.The GeoH2 Salt Storage and Cycling App is a web-based thermodynamic simulator, which consists of the following modules: (a) H2 physical properties, (b) volumetric, (c) production, (d) injection, and (e) cycling. The physical properties module provides the user with the main thermodynamic, transport, and thermal properties of H2. The volumetric module allows the user to estimate H2 storage capacities in salt caverns. The production and the injection modules simulate the withdrawal and the injection of H2, respectively. Finally, the cycling module models sequential withdrawal and injection processes.This study validates the results of the physical properties and the volumetric modules with real data. We validate the results of the production and the injection modules for synthetic cases using an open-source thermodynamic simulator.This work presents a novel tool suitable to assess the technical potential of H2 storage, injection, withdrawal, and cycling operations in salt caverns. This application can also be used, along with subsurface geological information, as a first order screening tool to assess H2 storage capacity at a regional or hub scale.