  In 2013, Henn proposed a special basis for a certain class of master
integrals, which are expressible in terms of iterated integrals. In this basis,
the master integrals obey a differential equation, where the right hand side is
proportional to $\epsilon$ in $d=4-2\epsilon$ space-time dimensions. An
algorithmic approach to find such a basis was found by Lee. We present the tool
epsilon, an efficient implementation of Lee's algorithm based on the Fermat
computer algebra system as computational backend.
