Uilleann is an iPhone app developed by Michael Eskin, offering an authentic 3/4 set of Uilleann pipes (Irish Bagpipes) chanter, drones, and regulators. It simulates playing these instruments through a standard two-octave piano keyboard interface, supporting hardware MIDI bagpipes chanters via a MIDI interface. The app provides a unique experience by allowing users to play in the four most common keys of D, C#, C, and B.

Users can toggle drones on and off by touching the drone puck image and play chanter notes by touching the keys. The app enables pitch bending and vibrato effects by touching different parts of the keys, mimicking real instrument techniques. Additionally, users can play regulator chords by touching squares above the keyboard, offering a comprehensive Uilleann pipes playing experience.

Uilleann also functions as a CoreMIDI sound module for MIDI file player apps, enhancing its versatility for musicians looking to integrate it into their MIDI setups.