PerMuVAR -- a MuPAD library for invariants of permutation groups. PerMuVAR was an open source library for the computer algebra system MuPAD for computing in invariant rings of permutation groups. The purpose was to study (at least partially) permutation groups that are too big to be treated by general invariant theory software. The main design goals were the following: Computation timepredictability (algorithms based only on linear algebra, no Gröbner basis computations); Reusability and extensibility (object oriented programming); Efficiency (Use of special properties of permutation groups; use of external specialized libraries for critical sections). PerMuVAR is now integrated in MuPAD-Combinat.