MongooseIM

MongooseIM is a high‑performance, fault‑tolerant XMPP server written in Erlang/OTP that serves as the backbone of an enterprise‑grade instant messaging platform. It implements the full XMPP core protocol stack, plus extensions such as PubSub, MUC, and BOSH, while also exposing a modern REST and SSE interface for non‑XMPP clients. The server is designed to run in a clustered environment, automatically balancing load across nodes and providing seamless failover for user sessions. Its modular architecture allows developers to drop in custom modules or replace built‑in components without recompiling the core.

Key Features

• Multi‑protocol support – Native XMPP, WebSocket/BOSH over HTTP, REST API, and Server‑Sent Events (SSE) for real‑time notifications.
• Clustered operation – Erlang’s distributed runtime handles node discovery, message routing, and state replication.
• Extensible plugin system – mongooseim modules can be added or replaced at runtime; the platform ships with a rich set of ready‑to‑use plugins for presence, message archiving, and authentication backends.
• Metrics & monitoring – Built‑in Prometheus exporters, a lightweight web UI, and an integration point for external monitoring tools.
• Load testing & CI – The project ships a comprehensive test suite, load‑testing harness, and continuous integration pipelines (GitHub Actions & CircleCI) to ensure reliability under production workloads.

Technical Stack

MongooseIM’s core is a collection of OTP applications (mongooseim, mod_* plugins, and shared utilities). Each plugin exposes a simple OTP behaviour (gen_server, gen_fsm) that can be swapped or extended by developers, enabling custom routing logic, message transformations, or integration with external services (e.g., a Kafka event bus).

Core Capabilities & APIs

• Session Management – mongooseim:register_user/3, mongooseim:login/2 expose a programmatic API for account creation and authentication.
• Message Routing – Developers can hook into the mod_message pipeline to implement custom filtering, moderation, or content‑based routing.
• Presence & MUC – Built‑in Multi‑User Chat rooms and presence subscriptions can be customized via configuration or plugin code.
• REST & Webhooks – Exposes CRUD endpoints for users, groups, and messages; supports webhook callbacks on events such as message delivery or presence changes.
• Admin API – A lightweight JSON‑over‑HTTP admin interface allows runtime configuration changes, node health checks, and cluster topology queries.

Deployment & Infrastructure

• Self‑hosting – MongooseIM runs on any Linux distribution that supports Erlang. The Docker image is pre‑configured with default clustering, making it trivial to spin up a multi‑node cluster.
• Scalability – Horizontal scaling is achieved by adding nodes to the cluster; Erlang’s distributed messaging automatically routes packets. The platform can handle millions of concurrent users with minimal per‑node overhead (~200 MB RAM).
• Containerization – The official Docker image supports sidecar patterns (e.g., Prometheus exporter, log shipper). Helm charts provide all‑in‑one Kubernetes manifests with customizable resource limits and persistent volumes.
• High Availability – Mnesia replication or external databases ensure session persistence across node failures; the BOSH/WebSocket fallback guarantees client reconnection without manual intervention.

Integration & Extensibility

• Plugin Ecosystem – Any OTP module that implements the expected behaviour can be dropped into mods directory. Examples include custom authentication (mod_auth_ldap, mod_auth_jwt) and message processing (mod_filter_spam).
• Webhooks & Callbacks – Developers can register callback functions for events such as on_message, on_presence, enabling real‑time integrations with analytics or notification services.
• External APIs – The REST interface can be consumed by web frontends, mobile SDKs, or third‑party bots.
• Custom Protocols – The modular design allows adding new transport adapters (e.g., MQTT, AMQP) via OTP behaviours without touching the core.

Developer Experience

• Documentation – The official docs (esl.github.io/MongooseDocs) cover installation, configuration, API references, and advanced topics. The guide includes a detailed testing section that demonstrates how to write common_test suites against the running server.
• Community & Support – Active GitHub repository, open‑source contributions, and commercial support from Erlang Solutions.
• Configuration – A declarative config file (YAML/JSON) lets developers enable or disable plugins, set database backends, and tune cluster parameters.
• Testing – Built‑