Simple, link-centric user profiles might seem might not seem like a particularly ambitious idea, but it’s been big enough for Linktree. The Melbourne startup says that 8 million users — whether they’re celebrities like Selena Gomez and Dua Lipa or brands like HBO and Red Bull — have created profiles on the platform, with those profiles receiving more than 1 billion visitors in September. Plus, there are more than 28,000 new users signing up every month. “This category didn’t exist when we started,” CEO Alex Zaccaria told me.