High-Dimensional Integrator. HDIntegrator (Honkonen 2017) is a program for parallel numerical integration of functionsin arbitrary number of dimensions. It is implemented in Python and parallelized usingthe Message Passing Interface (Forum 1995) via mpi4py (Dalcín, Paz, and Storti 2005).HDIntegrator is a wrapper program that divides the integration region into rectangularsubvolumes and uses a separate serial program (the integrand) for evaluating the integralwithin those subvolumes. Integration of a subvolume is stopped when one of the user-specified criteria for convergence is fulfilled, otherwise the subvolume is divided into twosmaller subvolumes and integration is continued. Communication between HDIntegratorand integrand is handled via standard input and output in ASCII format.