In February 2018, GRChombo, a new COSMOS Consortium code for numerical general relativity simulations targeted at theoretical physics applications, was made open source. It is developed primarily by a consortium of physicists from Argonne National Laboratory, Cambridge University, Göttingen University, King’s College London and Queen Mary University of London, in close collaboration with the COSMOS Intel Parallel Computing Centre at DAMTP Cambridge. GRChombo is maintained by a collaboration of numerical relativists and cosmologists with a wide range of research interests, from early universe cosmology to astrophysics and mathematical general relativity. Further information can be found at www.grchombo.org, including details of how to obtain and use the code. The GRChombo team hopes that this will be a useful resource for other researchers wishing to investigate the effects of strong gravity in fundamental physics. The next release of GRChombo (version 1.1) will shortly incorporate in-situ or “on the fly” visualization capabilities for AMR grids which were developed as part of the Software-Defined Visualization collaboration involving Intel, TACC and COSMOS IPCC (see sdvis.org)