  We introduce matchmakereft, a fully automated tool to compute the tree-level
and one-loop matching of arbitrary models onto arbitrary effective theories.
Matchmakereft performs an off-shell matching, using diagrammatic methods and
the background field method when gauge theories are involved. The large
redundancy inherent to the off-shell matching together with explicit gauge
invariance offers a significant number of non-trivial checks of the results
provided. These results are given in the physical basis but several
intermediate results, including the matching in the Green basis before and
after canonical normalization, are given for flexibility and the possibility of
further cross-checks. As a non-trivial example we provide the complete matching
in the Warsaw basis up to one loop of an extension of the Standard Model with a
charge -1 vector-like lepton singlet. Matchmakereft has been built with
generality, flexibility and efficiency in mind. These ingredients allow
matchmakereft to have many applications beyond the matching between models and
effective theories. Some of these applications include the one-loop
renormalization of arbitrary theories (including the calculation of the
one-loop renormalization group equations for arbitrary theories); the
translation between different Green bases for a fixed effective theory or the
check of (off-shell) linear independence of the operators in an effective
theory. All these applications are performed in a fully automated way by
matchmakereft.
