Mattermost - Mattermost is an open source alternative to Slack.
Arcat.XP - Arcat.XP is an Event Management Software that helps organizers, attendees, exhibitors, and sponsors to manage their events with ease from start to finish.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Digitevent - The powerful software to manage your event participants.
Slack - A messaging app for teams who see through the Earth!
Wisembly - Find out more about Wisembly, the web & mobile solution which you can use to prepare and hold your meetings, and ensure they are followed up.