Backchannel Chat - Backchannel Chat is best in class discussion tool that is intended for teachers to streamline their class activities.
Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
NowComment - NowComment is a complete suite of collaboration tools, streamlining group discussion, annotation, and curation of texts, images, and videos.
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
Eduflow - Digital learning that actually teaches students something
MailChimp - MailChimp is the best way to design, send, and share email newsletters.