Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Membee - Membee is web-based membership management software.
Influitive - Influitive helps companies increase customer lifetime value and accelerate sales with the power of their own customer advocates. Inspire your customers to stay longer, share their experiences, and attract new business.
Galette - Galette is a membership management web application towards non profit organizations.