  We present the interface between MadGraph5_aMC@NLO, a self-contained program
that calculates cross sections up to next-to-leading order accuracy in an
automated manner, and APPLgrid, a code that parametrises such cross sections in
the form of look-up tables which can be used for the fast computations needed
in the context of PDF fits. The main characteristic of this interface, which we
dub aMCfast, is its being fully automated as well, which removes the need to
extract manually the process-specific information for additional physics
processes, as is the case with other matrix element calculators, and renders it
straightforward to include any new process in the PDF fits. We demonstrate this
by studying several cases which are easily measured at the LHC, have a good
constraining power on PDFs, and some of which were previously unavailable in
the form of a fast interface.
