MongooseIM is an open source instant messaging platform designed to support large-scale enterprise deployments. It provides high-performance, reliable and extensible real-time messaging and communication services for mobile, web, and desktop applications. MongooseIM is built on the Erlang/OTP platform, an industrial-grade technology for building distributed, resilient and fault-tolerant systems. Its core features include extensible message routing, distributed presence and offline messaging, multi-user chat, and an extensible framework for authentication, authorization and data storage. MongooseIM also provides support for popular messaging protocols such as XMPP, MQTT, and WebRTC. It is compatible with a wide range of client applications, making it an ideal platform for building secure, real-time communication applications. MongooseIM is an open source project developed by Erlang Solutions, and is used by businesses worldwide.
Discontinued As noted at https://github.com/sdelements/lets-chat/issues/781, the project is no longer in development as of August 2017. The latest version, 0.4.0, released in June 2015, can still be downloaded from GitHub along with the source code.
Discontinued https://alternativeapp.info/software/slack/ is acquiring Hipchat and https://alternativeapp.info/software/stride-by-atlassian/ from Atlassian. services will be discontinued after February 15, 2019. https://www.atlassian.com/partnerships/slack