The Pencil Code Collaboration, Axel Brandenburg, Anders Johansen, Philippe A. Bourdin, Wolfgang Dobler, Wladimir Lyra, Matthias Rheinhardt, Sven Bingert, Nils Erland L. Haugen, Antony Mee, Frederick Gent, Natalia Babkovskaia, Chao-Chin Yang, Tobias Heinemann, Boris Dintrans, Dhrubaditya Mitra, Simon Candelaresi, Jörn Warnecke, Petri J. Käpylä, Andreas Schreiber, Piyali Chatterjee, Maarit J. Käpylä, Xiang Yu Li, Jonas Krüger, Jørgen R. Aarnes, Graeme R. Sarson, Jeffrey S. Oishi, Jennifer Schober, Raphaël Plasson, Christer Sandin, Ewa Karchniwy, Luiz Felippe S. Rodrigues, Alexander Hubbard, Gustavo Guerrero, Andrew Snodin, Illa R. Losada, Johannes Pekkilä, Chengeng Qian. The Pencil Code, a modular MPI code for partial differential equations and particles: multipurpose and multiuser-maintained. J. Open Source Software, 6(58):2807, 2021. [doi]