Model-based testing (MBT) is about testing a software system by using a model of its behaviour. To benefit fully from MBT, automation support is required. This paper presents a systematic review of prominent MBT tool support where we focus on tools that rely on state-based models. The systematic review protocol precisely describes the scope of the search and the steps involved in tool selection. Precisely defined criteria are used to compare selected tools and comprise support for test coverage criteria, level of automation for various testing activities, and support for the construction of test scaffolding. The results of this review should be of interest to a wide range of stakeholders: software companies interested in selecting the most appropriate MBT tool for their needs; organizations willing to invest into creating MBT tool support; researchers interested in setting research directions.