  The intricated combinatorial structure and the non-compactness of the Lorentz
group have always made the computation of $SL(2,\mathbb{C})$ EPRL spin foam
transition amplitudes a very hard and resource demanding task. With
\texttt{sl2cfoam} we provide a C-coded library for the evaluation of the
Lorentzian EPRL vertex amplitude. We provide a tool to compute the Lorentzian
EPRL 4-simplex vertex amplitude in the intertwiner basis and some utilities to
evaluate SU(2) invariants, booster functions and $SL(2,\mathbb{C})$
Clebsch-Gordan coefficients. We discuss the data storage, parallelizations,
time, and memory performances and possible future developments.
