The quasinormal modes of black holes—which are mode-like solutions to the linearized Einstein equations about a black hole background—are thought to describe the relaxation (the “ringdown”) of the remnant black hole formed after the merger of black holes. I discuss how hyperboloidally compactified coordinates are a particularly convenient set of coordinates to study black hole quasinormal modes. I describe several numerical experiments that use hyperboloidally compactified coordinates to study how well the ringdown could be described by a sum of quasinormal modes. Finally, I review several open-source codes developed to conduct those experiments.