Topicbox - Put team emails into one centralized, searchable place
Facebook Groups - This app gives you a dedicated space for you and your groups
InboxSDK - First usable API to write Gmail Apps for 1B active users
Mobilize - Mobilize is a scalable messaging app built for large groups.
Inbox Grader by Freshworks - Free metrics 📈 for your business and team email ✉️
Telegram Desktop - Fast and secure desktop messaging app, now updated