Macroevolutionary processes dictate the generation and loss of biodiversity. Understanding them is a key challenge when interrogating the earth–life system in deep time. Model-based approaches can reveal important macroevolutionary patterns and generate hypotheses on the underlying processes. Here we present and document a novel model called REvoSim (Rapid Evolutionary Simulator) coupled with a software implementation of this model. The latter is available here as both source code (C++/Qt, GNU General Public License) and as distributables for a variety of operating systems. REvoSim is an individual-based model with a strong focus on computational efficiency. It can simulate populations of 10 5 –10 7 digital organisms over geological timescales on a typical desktop computer, and incorporates spatial and temporal environmental variation, recombinant reproduction, mutation and dispersal. Whilst microevolutionary processes drive the model, macroevolutionary phenomena such as speciation and extinction emerge. We present results and analysis of the model focusing on validation, and note a number potential applications. REvoSim can serve as a multipurpose platform for studying both macro and microevolution, and bridges this divide. It will be continually developed by the authors to expand its capabilities and hence its utility.