Ensuring the success of organisations in their transition to a circular economy requires providing them with tools capable of measuring, monitoring and communicating their progress. That is, there is a need for tools that allow them to make a diagnosis of the current situation from which to establish objectives and goals in the short, medium and long term, while also enabling them to monitor the extent to which they are fulfilled. The aim of this study is thus to carry out a review of 10 tools specifically developed to measure the level of circularity of organisations and to perform an in-depth analysis of their general characteristics (ownership, launch date, interface, availability, language, application cases and training materials), required information (questions, categories and input data) and the results that can be obtained and the way in which they are communicated. This review shows that the number of circular assessment tools has increased in recent years, although there is a clear lack of harmonisation in terms of characteristics and content. It is concluded that these tools can be useful as a first starting point, but it is necessary to consider that when using them for decision-making, the results obtained in the same application could differ significantly depending on the tool applied.