  The semiclassical approximation of the worldline path integral is a powerful
tool to study nonperturbative electron-positron pair creation in
spacetime-dependent background fields. Finding solutions of the classical
equations of motion, i.e. worldline instantons, is possible analytically only
in special cases, and a numerical treatment is nontrivial as well. We introduce
a completely general numerical approach based on an approximate evaluation of
the discretized path integral that easily and robustly gives the full
semiclassical pair production rate in nontrivial multi-dimensional fields, and
apply it to some example cases.
