What about Mattermost, how is this different?
Gitter was built to be used in the open. We’ve always seen Gitter as a network, or a place where people can come to connect to one another. Team collaboration, whilst possible, has never been a core aspect of the Gitter experience.
Mattermost is a powerful, integrated messaging product for team collaboration - we will continue to ship and recommend using Mattermost for internal team communication.