Dating apps: do they all have the same purpose?

Here in Brazil, Tinder is mostly used for sex, but I have a friend who's dating someone she knew through Tinder 4 years ago. My second partner was from Tinder too, but well, we didn't last long. Six months only. Then there's Happn and OkCupid - the latter is more used by people looking for long-term relationships.

Gay apps are almost all focused on sex: Grindr, Scruff and Hornet are filled with naked torsos and unsolicited dick pics.