Functions to compute Euclidean minimum spanning trees using single-, sesqui-, and dual-tree Boruvka algorithms. Thanks to K-d trees, they are fast in spaces of low intrinsic dimensionality. Mutual reachability distances (used in the definition of the 'HDBSCAN*' algorithm) are supported too. The package also includes relatively fast fallback minimum spanning tree and nearest-neighbours algorithms for spaces of higher dimensionality. The 'Python' version of 'quitefastmst' is available via 'PyPI'.