Tests of absolute model fit are crucial in model-based inference because poorly structured models can lead to biased parameter estimates. In Bayesian inference, posterior predictive simulations can be used to test absolute model fit. However such tests have not been commonly practiced in phylogenetic inference due to a lack of convenient and flexible software. Here we describe newly implemented tests of model fit testing using posterior prediction, based on both data- and inference-based test statistics, in the phylogenetics software RevBayes. This new implementation makes a large spectrum of models available for use through a user-friendly and flexible interface.