AIMSim is a completely open-source cheminformatics software designed for code-free utilization as well as a Python package for more specialized programmatic usage. From a user-friendly graphical user interface, AIMSim can calculate similarity density distributions, similarity heatmaps, single-molecule database comparisons, and dimensionality reductions to facilitate research in various fields. Nearly 50 common distance metrics used in cheminformatics are available via AIMSim, as well as a host of molecular fingerprints and descriptors. AIMSim's full parallelization, supporting multiprocessing capabilities, greatly boosts performance. Thus, AIMSim can tractably analyze large-scale datasets typical in machine learning applications.