Musical.ly is now TikTok, as predicted

Last November, when ByteDance bought Musical.ly, I wrote that the thing to watch was the recommendation engine and not the lip-sync. Last week ByteDance shut down the Musical.ly brand and moved all its users into TikTok, the international version of Douyin. If you open the old app now, it updates into TikTok.

The biggest visible change is the feed. Musical.ly was organized around who you follow. TikTok opens on the “For You” page: full screen, one video at a time, swipe for the next, chosen by the algorithm based on what you’ve watched. You don’t need to follow anyone for it to be good. It gets good in about twenty minutes of use, which is faster than anything I’ve used, because every fifteen-second video is a new data point.

The design choices all serve the recommender. Full screen, one video at a time, means every video gets an unambiguous signal: did you watch it through, rewatch, swipe early, like, share, or follow the creator. There’s no grid of thumbnails where you pick one and the system has to guess why. Autoplay with sound on means you react to the actual content, not the cover image. Short videos mean hundreds of reactions per session. It’s a machine for producing training data about your taste, and the user experience is designed around that.

The other thing I notice is how creation is built in. The app has music, effects, speed controls and templates, so a lot of the content is people remixing the same song or trend in their own way. That gives the recommender many variations of the same idea, and it can learn which variations work for whom.

I said in November that I expected TikTok to be one of the fastest-growing apps in the US within two years. Having used it for a week, I’d shorten that. And I think every other social company is going to have to decide soon whether to copy the For You model, because once people get used to a feed that doesn’t need their friends to be interesting, a feed that does starts to feel empty.