Ask HN: Alternatives to Facebook Events and Messenger?

Does anyone know of a good alternative to Facebook Events + Messenger for organizing events and chatting with social groups. I'm part of an organization that travels to different events a lot and uses a combination of Facebook Events and Messenger to track RSVPs and chat about the events. However, we're all pretty eager to get off Facebook. I've been looking around today and haven't really found any alternatives that provide the same functionality. Anybody know of some good options?