Hookup apps can be a great place to find FWB, whether you're looking for a more casual version of the relationship or an actual friend with whom you also happen to hook up. Apps like Tinder and Pure are more on the casual end of the spectrum, while you might check out apps like Hinge or OkCupid to find people you'd want to sleep with and hang out with. Kinky folks can also check out more community-oriented platforms such as FetLife.