ejabberd

ejabberd is a free, open-source XMPP server written in the Erlang programming language. It was developed by ProcessOne and is maintained by ProcessOne together with the broader community. The project aims to provide a scalable, reliable platform for real-time messaging and is distributed under the GNU General Public License.

Key features of ejabberd include support for the XMPP core protocol and commonly used extensions, horizontal scalability through clustering, and high availability across multiple nodes. It provides multi-user chat (MUC), publish-subscribe (PubSub), message archiving, and offline messaging. Security and transport are supported via SASL authentication, TLS encryption, and modern transport options such as WebSocket and BOSH to accommodate a variety of network environments.

ejabberd follows a modular architecture with a wide range of components (modules) for authentication, storage, and features. Data storage is flexible: by default it uses the Mnesia database but can also connect to external SQL backends like PostgreSQL and MySQL for larger deployments. The server offers a web-based administration interface and a comprehensive HTTP API for automation and management.

Deployment and reception: ejabberd runs on multiple platforms and is widely used for both enterprise and community XMPP services due to its maturity and extensibility. The project supports ongoing development and a broad ecosystem of extensions, making it suitable for small teams as well as large-scale deployments.