Whoin is a social networking app designed for iPhone users, developed by Ethan Millstein. It falls under the Social & Communication category, specifically catering to social networking needs. Whoin offers a convenient solution for organizing impromptu gatherings with friends without the hassle of individual messages or group chats.

With Whoin, users can effortlessly plan activities like dinner outings, movie nights, workouts, and more by creating posts detailing the plan and timing. The app simplifies the process of gauging interest and availability, allowing users to quickly identify who's up for the proposed activity. Whoin provides a casual and efficient way to connect with friends for spontaneous meetups.