Besides the ''vasp2trace'' code, which computes the traces of electronic bands, another open-source program ''irvsp'' is developed to determine irreducible representations of electronic states for all 230 space groups with an interface to the Vienna ab-initio Simulation Package. All the IRs are labeled in the convention of our BCS notation, which can be directly compared with the elementary band representations of topological quantum chemistry (TQC). This code is fed with plane-wave-based wavefunctions (e.g. WAVECAR) and space group operators (listed in OUTCAR), which are generated by the VASP package. It also works with spin-orbit coupling (SOC), i.e., for double groups. It is in particular useful to analyze energy bands, their connectivities, and band topology, after the establishment of the theory of TQC.