Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

Mobilize - Mobilize is a scalable messaging app built for large groups.

Galette - Galette is a membership management web application towards non profit organizations.

Crowded Communities - The all-in-one community platform.

Bigtent - BigTent is a web-based organization and communication portal for groups.

NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.