Often technology fails to benefit those not apt to using it, but iReal b by Technimo is an indispensable musician’s tool.
Available for Macintosh computers, iOS and Android, iReal b covers a lot of bases in availability. Useful for any student of music or gigging musician, iReal b is similar to a musician’s real book giving chord changes for thousands of tunes (because of copyright, there are no melodies), but a variety of jazz, Latin, pop and rock tunes are available, and you can program your own. But iReal b’s best feature is its built in music player. You can program your own chord changes and then have iReal b play them in a  variety of styles and at whatever tempo you choose.

For example, your band may be working on a song. You program the chord changes in then choose a “Latin – Brazil Bossa Electric” style, and set the tempo. Then change that to a “Pop – R&B” style to hear how different the song can sound. The player plays the bass, drum and piano parts. It’s a band in a box that no musician should be without.