exotrans is a software package developed by the Department of Planetary Research of the Rheinisches Institut für Umweltforschung (RIU-PF) at Cologne University for detecting transit signals from extrasolar planets in stellar light curves. exotrans is used very successfully by RIU-PF within the CoRoT mission. The software package uses two different filter algorithms for pre-whitening and noise reduction (harmonic and trend filtering). Three different box-fitting least-squares algorithms (BLS) are applied in order to extract a potential transit signal from the light curves. The performance of each filter-BLS-algorithm combination on real CoRoT data is presented and compared with other methods used by the CoRoT team.