Mattermost

Mattermost is an open source collaboration platform aimed at software teams and related operational groups. It provides workspaces where users can exchange messages, organize conversations by channels, and keep project communication in one place. The application is published by Mattermost, Inc. under the Apache-2.0 license, and this entry covers the Linux platform.

Its focus is team coordination rather than general document editing or project planning by itself. A typical use is to discuss code changes, deployments, incidents, support queues, and daily engineering work in persistent threads and channels. Organizations can use it as a developer-centered communication layer alongside issue trackers, source control systems, and other tools, while retaining the option to inspect and adapt the open source code.