Rocket.Chat is an active project for a self-hosted open-source alternative to Slack. The platform allows chat, file sharing, video conferencing, helpdesk and voice messaging services. Rocket.Chat typically works with multiple services including GitHub, GitLab, JIRA, Dolphin and Confluence. Rocket.Chat is an Internet of Things (IoT) application and is noted for running well on small IoT devices, including the Raspberry Pi Zero. Great choice, nice interface, easy to deploy. Supports: videoconference, helpdesk chat, file sharing, voice messages, link preview, API, Mobile App. It can be connected to Hubot!