The Clausula Archive of the Notre Dame Repertory (CANDR) is an in-progress project with the aim of cataloguing, transcribing and analysing digital facsimiles of the thirteenth-century repertory commonly termed Notre Dame polyphony, and a secondary aim of providing new datasets and analytical tools for studying medieval polyphony. CANDR is an online and open source database for thirteenth-century polyphony, augmented by an optical music recognition (OMR) and editing tool.