Happier by Marshmello & Bastille is in Bb at 100 beats per minute and runs 3:13 across 56 bars. It uses 10 chords — Dm7, C, F, Bb, N.C., Dm, D5, F5, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? Happier guitar melody tab.