We present a fast and user friendly exoplanet transit light-curve modelling package pytransit, implementing optimized versions of the Gimenez and Mandel & Agol transit models. The package offers an object-oriented python interface to access the two models implemented natively in fortran with OpenMP parallelization. A partial OpenCL version of the quadratic Mandel-Agol model is also included for GPU-accelerated computations. The aim of pytransit is to facilitate the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations, as a part of a researcher's programming toolkit for building complex, problem-specific analyses.