Locket Widget was meant to be a gift, a tiny app that connected developer Matt Moss to his girlfriend using photos and a clever Home Screen widget. But thanks to the viral power of TikTok, the app went from passion-fuelled side project to chart-topping sensation.

There’s a beautiful simplicity to the app: Snap a photo to send it directly to a friend’s Home Screen—then invite them to do the same for you. Pics arrive unannounced, so each time you unlock your iPhone there’s always the potential for surprise.

Locket’s innovative pairing of widgets with real-time photo updates made it a staple app for us this year. It helped us see small moments we might’ve missed (like our friend using the mug we gifted them a few years ago) and big moments we wish we hadn’t missed (like our cousin’s graduation). Sometimes it was just reassurance our loved ones were on their way home—and that we’d see them soon.

Locket doesn’t limit you to a single widget. You can dedicate different ones to different people (like your best friend or crush).

Developer Matt Moss had been using an early version of Locket with his girlfriend for about six months before he published it on the App Store.

Moss has developed apps since high school. A graduate of UC Santa Barbara, he’s been recognized as a WWDC student scholarship winner in 2017 and 2019. “Usually there’s this delta between how useful you think your app could be and how good it is to actually use,” he says. “Locket was one of the rare instances where the idea seemed really cool from the start.”