Augmented reality is the concept of taking a representation of the real world, adding something to it and displaying it to the user. Applications for smartphones—so called augmented reality browsers—typically take the image of the integrated camera as a representation of the real world, and project textual or graphical objects on top of this image to create the augmented reality. The user can now look 'through' their phone as if taking a picture to look at the augmented world. This report describes iBetelgeuse; a novel augmented reality browser for iPhone, designed to be compatible with the Gamaray browser for Android. iBetelgeuse was developed for Finalist IT Group to improve the availability of their current and future augmented reality applications, and is the result of our Bachelor's project. iBetelgeuse supports most features other browsers also support, but focuses on interaction and responsiveness. Like Gamaray, it supports interaction with objects in the virtual world by tapping them, and allows dynamic worlds to be displayed by means of a web service. Unlike Gamaray and most other browsers it is highly responsive to changes in device orientation, which leads to a better user experience. The project was performed using Scrum; a framework for agile software development. Scrum successfully guided us through the development process, which resulted in an ever working product as we progressed. The first few weeks were dedicated to orientation and research, which proved to be very useful. iBetelgeuse has a clean architecture and thoroughly tested implementation, fit for maintenance and extension. It employs various algorithms that are quite complex and that require some mathematical background and thorough reading of this document to be understood, but apart from those algorithms the implementation is generally easy to understand and well documented. Although iBetelgeuse is a fully functional product—currently being reviewed by Apple for publishing in the iPhone App Store—there are still enough areas that can be improved. Our most important recommendations revolve around changes affecting the user experience, although some aspects of the implementation can also be improved, and new features can be added. Our recommendations for the application of iBetelgeuse, Gamaray, and their web services are, in short, that the interface between the web service and browser should be extended to give the web service more control over what is displayed on the client. We suggest to use a KML based format to replace the currently used GDDF format.