Character.ai

Character.ai lets users create and chat with AI personas — fictional characters, historical figures, custom companions — built on its own model tuned for in-character conversation, and it's still one of the most heavily used AI platforms by time spent per session. Its founders left for Google in a 2024 licensing deal, and after facing lawsuits over harm to teenage users, the company banned open-ended chat for users under 18 in late 2025 and shifted toward more tightly supervised, entertainment-focused experiences.