The MeerKAT radio telescope has been producing high-quality scientific data for more than six years. Its Science Data Processor (SDP) subsystem produces signal displays, calibration products, continuum images and spectral cubes in a fully automated and pipelined fashion from the outputs of the correlator and tied-array beamformer. I review the major parts of the MeerKAT SDP pipeline with a focus on the software architecture, design choices and lessons learnt.