We present Jolab: an open source package for performing full-wave simulation of light propagation in optical systems. Jolab enables a very broad range or researchers, engineers and practitioners to simulate light propagation through complex optical systems. Jolab takes a relatively simple script as its input in which the optical system is defined and light is propagated by each optical components sequentially using built-in functions. Jolab scripts are simple and readable and their structure is designed to mimic the design of optical systems making it easy to learn. We will present a range of examples including time-domain simulations and wavefront-shaping experiments.