Mattermost.com

Mattermost is an open-source messaging and collaboration platform founded in 2015 by Ian Tien and Corey Hulen, headquartered in Palo Alto, California. The company builds a self-hostable alternative to cloud-based messaging tools, targeting organizations that require on-premises deployment, data sovereignty, or strict security controls, including defense, government, and regulated industries.

Mattermost's primary product is a team messaging platform that supports channels, direct messaging, file sharing, and integrations with developer tools such as GitHub, Jira, and Jenkins. The platform is available in open-source and commercial editions, with enterprise features including compliance exports, LDAP/SAML authentication, and high-availability configurations. Notable customers include the U.S. Department of Defense, which has deployed Mattermost within classified and air-gapped environments. The company also offers Mattermost Boards for project management and Playbooks for structured workflow automation.

Mattermost raised a $50 million Series B round in 2019 led by Redpoint Ventures, bringing total funding to approximately $70 million. The company operates with a distributed workforce and has grown its commercial customer base among defense contractors, financial institutions, and technology firms. Its open-source repository on GitHub has accumulated significant community contributions, underpinning both the free and enterprise product tiers.