Mattermost offers an enterprise-grade HipChat Data Center replacement with optional high availability deployment (scaling to 60K concurrent users in a single team), SAML/AD/LDAP and SSO integration, EMM and Enterprise App Store, support for mobile apps, data retention policies, integration with Actiance and Global Relay support for eDiscovery, compliance reporting as well as many other advanced features (read about Mattermost features).
Atlassian-Mattermost customers are succeeding daily with combined solutions, including Wargaming, creator of the “World of Tanks” video game franchise, which had over 2.6 million issues in its self-hosted Jira instance when it first integrated with Mattermost (see the video case study | read the case study).
A broad array of Atlassian tools integrate with Mattermost, including on-prem Jira and Confluence, with additional integrations continually provided (learn more about Mattermost-Atlassian integrations).
Mattermost is Slack-compatible. Slack users coming to on-premises Mattermost will find compatible keyboard shortcuts, navigation, slash commands and even theme colors. Moreover, Mattermost is compatible with Slack-webhook integrations, which means that any Atlassian or custom integration built for Slack-webhooks works with Mattermost as well. Unlike Slack, customers can run Mattermost in both on-prem and cloud environments (AWS, Azure, etc).