How we picked
Hookup sites differ in who's on them and how you pay. AdultFriendFinder is the general-purpose giant; FetLife and SDC are communities for kink and swinging; Ashley Madison is built around discretion and charges men per conversation.
We ranked them on the size of the community, what you can do for free, and pricing at the time of writing, using our reviews. Most charge men for messaging, so check the free tier before you pay.