Mu3e is a particle physics experiment at the Paul Scherrer Institute, searching for decays of anti-muons (Mu) to an electron and two positrons (3e). This decay is extremely unlikely in the Standard Model of particle physics, as it changes the lepton number. Several new theories, especially supersymmetric ones, predict a much more frequent decay. Searching for this decay allows a test of these theories, even if they cannot be tested directly in other experiments like at the LHC. It has also been shown the experiment is sensitive to probe new light dark sector particles such as dark photon.