Apple Events for macOS - The unofficial Apple Events app for macOS
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Facebook Local - Discover places to go and events happening near you
Bigtent - BigTent is a web-based organization and communication portal for groups.
TechEvents.co - Tech and startup events aggregator
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.