After more than a year developing time and a tough testing phase, we proudly present the first version of our web-based software mono:di to the interested public. Commissioned by the University of Würzburg, this tool facilitates editing of medieval chants in a way that can not be rivaled by any standard music notation application (be it open source or proprietary). While being a browser based tool that allows registered editors to collaborate online via a server managing their music, mono:di makes use of latest web technology to also enable offline work. As this technology is not yet consistently supported by all browsers, the application is designed to run in Google Chrome or Firefox. More information about the long-term editing project can be found on the corpus monodicum web page We are looking forward to your feedback!