Standing By by Pentatonix is in Gb at 112 beats per minute and runs 4:09 across 90 bars. It uses 9 chords — N.C., Db5, Gb5, Db, Gb, Ab, Bbm, Ab5, 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? Standing By guitar melody tab.