Euclid will measure redshifts of galaxies on 15,000 square degrees of the sky using slitless spectroscopy. In order to prepare for such an unprecedented amount of data, we are building a pipeline to simulate the procedure of measurement from start to finish, i.e. end-to-end simulations. We start from cosmological simulations of the distribution of dark matter in the universe with an assigned galaxy distribution and simulated spectra. Using this data as input, we then simulate the Euclid NISP instrument and generate slitless images. Such images are then analysed, spectra are extracted and redshifts are measured. The simulated catalogues we output emulate the redshift catalogues that will be produced by the true Euclid pipeline. We do this on a smaller scale to pixel-level precision, and approximately for simulating larger patches of the sky. Such mock measured catalogues serve as a basis for testing and developing data analysis tools and procedures for mitigating systematic effects in the measurement of galaxy clustering.