Cesam2k20 computes one-dimensional stellar structure and evolution models under the assumption of hydrostatic equilibrium. The code evolves stellar models from pre-main sequence through advanced evolutionary stages using modular numerical schemes and up-to-date microphysics. Cesam2k20 builds on the CESAM (ascl:1010.059) stellar evolution code and incorporates developments from related tools such as ADIPLS (ascl:1109.002) for asteroseismic applications. It includes treatments of processes such as chemical mixing, angular momentum transport, and rotation within a unified framework. Cesam2k20 supports stellar modeling studies in both classical and asteroseismic contexts.