Building a General Purpose Educational Augmented Reality Application: The case of ARTutor George Terzopoulos 1[0000-0001-6946-838X] , Ioannis Kazanidis 1[0000-0002-2034-0294] and Avgoustos Tsinakos 1[0000-0001-5043-0226] 1 International Hellenic University, Greece Abstract. Augmented Reality (AR) technology is constantly evolving. Nowa- days, there are AR platforms that allow educators to build AR experiences for their students. Most of these tools are not free and have specific domain orienta- tion, allowing instructors to use them for specific domains and courses. The main aim of this study is to provide details on the approach, design and development frameworks that developers have to follow in order to build a general- purpose educational AR tool. The available technologies will be presented and an opti- mum approach and design will be proposed. In addition, this study presents the architecture and the adopted technologies of the general-purpose educational AR platform ARTutor (Version 3), a free tool for educators and their students. Com- pared to other AR platforms, ARTutor is a completely free and easy-to-use tool. With ARTutor, educators can create augmented books and add virtual content on top of printed material. The new version of ARTutor is based on state-of-the-art technologies such as Google’s ARCore and Apple’s ARKit. Evaluation results with pre-service teachers revealed that ARTutor is a valuable tool for education and it provides an easy way to implement AR experiences thus it can be easily adopted by various educational approaches. Keywords: Augmented Reality Technologies, Educational Augmented Reality Platforms, General Purpose Augmented Reality platforms, Educational Tech- nology. 1 Introduction Augmented Reality (AR) technology brings the digital world into the real world. It enhances reality by adding virtual information and allowing users to interact with the real world and the AR experience simultaneously. An AR experience can be viewed on a mobile device (smartphone or tablet) or even on smart glasses. Smart glasses are con- sidered the next big breakthrough for wearables and they will merge what we see in the real world with virtual information. AR technology can be used in various fields such as games, military, medical, industry and education. Engaging with internationally focused literature, some of the most popular fields of education that use AR in teaching are Science [1], Ecology [2], Natural Sciences [3], Physics [4], Geometry [5], Chemistry [6], Mathematics [7], Writing Skills [8], and