Аккорд (бесплатный выпуск) is an Android application developed by temerov that aims to help users learn the basics of music theory required to play the accordion and learn to play the instrument's right keyboard. The program offers training in musical intervals and notes, as well as exercises to play on the right keyboard, including ranges, random notes, only white keys, a certain octave, and all keys. Each exercise is accompanied by a brief reference to the theory.

In addition, the full version of the program includes the ability to play music from midi-files included in the program or added to the library. Users can also customize the appearance and duration of musical intervals. Аккорд (бесплатный выпуск) is an excellent educational and reference tool for anyone looking to learn the basics of music theory and play the accordion.