konto_check_ruby is a plain Ruby port (no C extension) of Michael Plugge's C library konto_check. It validates German bank account numbers with all check digit methods of the Deutsche Bundesbank (00 to E4), generates and validates IBANs including the Bundesbank IBAN rules, and looks up bank data (name, BIC, place, ...). It reads the LUT files of the original library as well as the bank code files (Bankleitzahlendatei) published by the Deutsche Bundesbank and can generate LUT files itself. The modules KontoCheck and KontoCheckRaw are compatible with the original konto_check gem.