Open Access Repository Ranking (OARR) ranks open access repositories from Germany, Austria and Switzerland. The ranking is based on an open and transparent metric that was developed in accordance with the open access community. The data for the 2015 ranking was partly submitted by the respective repository managers, and partly automatically validated via the OAI interfaces. The OARR team reviewed all submissions assuring the quality and validity. The preceding January each open access repository listed in BASE that meets the OARR definition will be included in the new ranking; the respective repository managers will be contacted later on to submit their data via an online form. The final ranking is published annually at the Open-Access-Tage conference.