Interest Engine or Service for Mobile App?

Hello Indie Hacker Community!

I had a quick question. I am building a mobile app that has an "Interest" component to it. I was hoping to leverage either a service or an API that does something like Meetup's UI (see link). Does anyone know if such a thing exist or if a service like this exists? I don't seem to be using the correct string of search terms.

Thanks in advance for any help!