Augmented reality (AR) applications are getting popular since they integrate the real world and the virtual world. This paper focusses on AR applications for public and scientific libraries. There exist some projects and sample implementations of AR apps specially designed for libraries, but they are seldom found in practice. To identify whether there is potential for AR apps to be applied in libraries, the results of a qualitative study that has been performed among librarians working in public and scientific libraries in Austria and experts in augmented reality are presented. Searching for media, navigating to the correct location and displaying ancillary information, like ratings, reviews, secondary media, links, etc., has the highest potential for users according to the experts. AR apps for maintaining the bookshelfs of a library provide real benefit for librarians and are awarded high potential as well. Guided tours through libraries using AR-based apps lightens the load of the librarians to introduce new users to the library. The feasibility of an AR app for a library is demonstrated by introducing a prototype that supports library users with additional information on media and the library itself.