Passaggi is an improvisation and ornamentation practice app for historical performers. The app delivers high-quality audio backing tracks for personal practice, which, when used in conjunction with facsimiles or modern editions of historical sources, enable the user to develop skills in the areas of improvisation and ornamentation. Suitable for students, amateurs and professionals alike, the app features adjustable pitch and tempo settings and user-defined looping capabilities. Tracks are recorded using a sampled historical organ in a temperament appropriate to the repertoire and are designed to complement the pedagogy of historical treatises. The idea behind Passaggi springs from a desire, common to many performers of historical repertoires, to recreate aspects of the musical experience as it may have existed at the time a piece of music was written. Improvisation and ornamentation may form only one aspect of this wide-reaching desire, yet it is clear that in this area students and professionals would achieve more successful immersive study and practice if the harmonic and musical context for improvisation, ornamentation and diminution were more easily accessible.How many of us can open Dalla Casa’s Il vero modo… and sing the baseline to his exercise embellishing Striggio’s I dolci colli, for example? And how much more profitable would our practice of this exercise be if we could? How many more of us would practise improvising on a ground, if we had a ground? The Passaggi project will enable more effective exploration of historical sources and approaches by providing digitally some aspects of the innate and inherited musical awareness common to all musicians of the past that we strive to connect with in the twenty-first century.