In the age of high-precision low-energy experiments such as MUonE or
MEG, QED corrections start to become more and more important. To match
the experimental error, we have developed McMule, an easily extendable
framework for fully differential higher-order QED calculations of
scattering and decay processes involving leptons.
I will discuss some of the theoretical underpinning for McMule, notably the
$FKS^\ell$ IR subtraction scheme and massification, as well as some recent
phenomenological results we have obtained with McMule.
