Youdle is an audio-mixer app that allows you to collaborate with friends and family (no matter where they are in the world) to record a personalized rendition of the “Happy Birthday” song. You start by recording your track, then send an invite for others to join in. Once all the individual tracks are laid down, the initiator mixes them into one song and then sends the very memorable tune to your favorite birthday boy or girl. Each participant can add their pic, and the whole chorus gets to enjoy the final mix… fun, right?!