MAGELLAN: a tool to explore small fitness landscapes. In a fitness landscape, fitness values are associated to all genotypes corresponding to several, potentially all, combinations of a set of mutations. In the last decade, many small experimental fitness landscapes have been partially or completely resolved, and more will likely follow. MAGELLAN is a web-based graphical software to explore small fitness/energy landscapes through dynamic visualization and quantitative measures. It can be used to explore input custom landscapes, previously published experimental landscapes or randomly generated model landscapes.