Tunebook for iPad is a viewer for music expressed in the ABC format, a simple text-based notation widely used for traditional folk music. You can import ABC format files from websites into its database, enabling you to list, search, and organize tunes based on title, key, and time signature. This program allows you to view tunes in musical notation and play them in various voices, as well as create tunebooks to manage your collection efficiently.

Based on abc2ps, fluidsynth, and the GeneralUser GS soundfont, Tunebook is licensed under GPL. For those interested, the source code can be accessed at the provided link. It's a handy tool for musicians looking to explore and enjoy tunes in the ABC format seamlessly.