Two written works by Du Fay have been documented, but neither has survived. A note in the margin in a manuscript held in the Biblioteca Palatina in Parma refers to a Musica which he wrote; no copy of the work itself has been found. Nineteenth-century musicologist François-Joseph Fétis claimed to have seen a sixteenth-century copy of a Tractatus de musica mensurata et de proportionibus by Du Fay, last documented as having been sold to a London book dealer in 1824. The contents of neither work are known.
Du Fay composed in most of the Common forms of the day, including masses, motets, Magnificats, hymns, simple chant settings in fauxbourdon, and antiphons within the area of sacred music, and rondeaux, ballades, virelais and a few other chanson types within the realm of secular music. None of his surviving music is specifically instrumental, although instruments were certainly used for some of his secular music, especially for the lower parts; all of his sacred music is vocal. Instruments may have been used to reinforce the voices in actual performance for almost any of his works. Seven complete Masses, 28 individual Mass movements, 15 settings of chant used in Mass propers, three Magnificats, two Benedicamus Domino settings, 15 antiphon settings (six of them Marian antiphons), 27 hymns, 22 motets (13 of these isorhythmic in the more angular, austere 14th-century style which gave way to more melodic, sensuous treble-dominated part-writing with phrases ending in the "under-third" cadence in Du Fay's youth) and 87 chansons definitely by him have survived. Of Du Fay's masses, his Missa se la face ay pale and Missa L'Homme armé are listed on AllMusic as essential compositions.
Most of Du Fay's secular songs follow the formes fixes (rondeau, ballade, and virelai), which dominated secular European music of the 14th and 15th centuries. He also wrote a handful of Italian ballate, almost certainly while he was in Italy. As is the case with his motets, many of the songs were written for specific occasions, and many are datable, thus supplying useful biographical information.
Du Fay was one of the last composers to make use of late-medieval polyphonic structural techniques such as isorhythm, and one of the first to employ the more mellifluous harmonies, phrasing and melodies characteristic of the early Renaissance. His compositions within the larger genres (masses, motets and chansons) are mostly similar to each other; his renown is largely due to what was perceived as his perfect control of the forms in which he worked, as well as his gift for memorable and singable melody. During the 15th century he was universally regarded as the greatest Composer of his time, an opinion that has largely survived to the present day.
