Mattermost

Open-core, self-hosted collaboration platform offering chat, workflow automation, voice calling, screen sharing, and AI integration. Written in Go and React, runs as a single Linux binary with PostgreSQL, released monthly under MIT license.

Trusted by governments, enterprises, and militaries for mission-critical environments including the U.S. Department of Defense and U.S. Air Force. Differentiates from cloud-only tools by enabling full data control, air-gapped and on-premises deployment, and sovereignty over infrastructure.

Key capabilities:

• Real-time chat with channels, threads, and file sharing
• Workflow automation via playbooks and slash commands
• Native audio calling and screen sharing
• 700+ integrations, webhooks, APIs, and plugin ecosystem
• Deployable on-premises, in private cloud, or Kubernetes
• Advanced compliance, auditing, and identity controls

Technical teams use Mattermost for DevSecOps ChatOps in regulated environments, incident response workflows, IT service desk coordination, and out-of-band communication during security events. Integrations with CI/CD, monitoring tools, and custom apps keep deployment and operations in a single collaboration hub.