Users can search by title, opus number, composer, conductor, orchestra, ensemble, instrument, period and soloist, among other parameters. Like a GPS for classical music, the app allows for highly detailed, deliberate searches, but its 50 million data points also facilitate easy discovery and a delightful sense of serendipity. A themed playlist from Khatia Buniatishvili will lead you in one direction; a “Track by Track” walk-through by pianist Víkingur Ólafsson through his album “Mozart & Contemporaries” will lead you in another.