Chatbots are used in different areas such as customer service, healthcare and education. The potential for improving outcomes and processes in education is high but differs for different types of chatbots. As universities want to provide excellent teaching, it is important to find the chatbot technologies with the greatest possible benefit. This paper presents a systematic review of chatbot technologies in five application areas. For each application area, the ten most cited publications are analysed and a possible categorisation scheme for chatbot technologies is derived. Furthermore, it is investigated which chatbot technology types are used and their suitability for higher education is analysed. The results show that chatbots can be categorised using five categories derived from the 50 publications. A total of 14 different types of chatbot technologies are found in the five areas. Nine of them are suitable for use in higher education.