For roleplays the biggest AI websites I've been using is Janitor.AI and Joyland.AI. Both are completly free to use for whatever usage you want, NSFW, role-playing, or even companionship if you wish.
As of currently, Joyland.AI hasn't really been using coins to chat with bots per message, so it's kinda free; tho there are in-app/in-browser purch......
