Slack, Microsoft Teams, Discord, Mattermost, Kosmi, Matrix.org, Zulip, Hack Chat, Flowdock, Guilded, Output Messenger, Ripcord, Wiggio, Kandan, uShare.to, HipChat, SVYFT, articlebox, Jaconda, Slenke, JANDI, Protonet SOUL, Hyphen Messaging, Skarpline are some alternatives to Gitter.