SplitsTree is a popular freeware program for inferring phylogenetic trees, phylogenetic networks, or, more generally, splits graphs, from various types of data such as a sequence alignment, a distance matrix or a set of trees. SplitsTree implements published methods such as split decomposition, neighbor-net, consensus networks, super networks methods or methods for computing hybridization or simple recombination networks. It uses the NEXUS file format. The splits graph is defined using a special data block (SPLITS block).