... collaboration. DevOps teams use Mattermost to power collaboration at every stage of the DevOps lifecycle. Mattermost unifies people, tools, data, and automations to help your team increase innovation and agility. Mattermost is an open source Slack alternative. It's written in Golang and React and runs as a single Linux binary with MySQL or PostgreSQL. Use the features you like (file sharing, real-time group chat and webhooks—to name a few) and access the source code.