Mattermost

Mattermost is a free, open-source team chat platform built for secure, real-time communication. It supports messaging, file sharing, and workflow automation, and can be self-hosted for full control over your data. It’s a strong Discord and slack alternative for organizations needing privacy, customization, and reliability.

Key features include:

• Adaptable Integrations: Extends collaboration with custom apps and industry-standard tools.
• Focused Workflows: Deep integrations, integrated playbooks, and native audio calling.
• Robust Security: Compliance features ensure data control and security.
• Resilient Infrastructure: Supports self-hosted, private cloud, and high-availability deployments.

Use cases include:

• Integrated Security Operations
• Self-Sovereign Collaboration
• Mission-Critical ChatOps
• Real-Time DevSecOps Collaboration