NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Crowded Communities - The all-in-one community platform.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
FUEL CYCLE by Passenger - Think Passenger builds online platforms that allow brands to connect, create and communicate with key stakeholders.
Bylde - Bylde is a SaaS platform you can use to Start, Manage and Grow your groups and communities.