Mobilizon

Mobilizon is a self‑hosted, federated platform for creating, sharing, and discovering events and activities. Built with the principles of the fediverse in mind, it allows multiple independent instances to interoperate using ActivityPub. The application is designed for developers who need a flexible, open‑source event management system that can be extended and integrated into existing ecosystems without vendor lock‑in.

Technical Stack

Mobilizon is written in Elixir and runs on the Phoenix web framework, which provides a highly concurrent, fault‑tolerant runtime ideal for real‑time features such as notifications and live updates. The backend relies on PostgreSQL for relational storage, while Redis is used for caching and background job queues (via Oban). The front‑end is a single‑page application built with React and TypeScript, communicating with the Phoenix server through a JSON‑API compliant REST layer. For geocoding, Mobilizon integrates with the open OpenStreetMap Nominatim service.

Core Capabilities

• Event lifecycle management: Create, edit, draft, and publish events; support for recurring activities.
• Participation handling: RSVP system with email notifications, attendee lists, and capacity limits.
• Group and community tools: Public pages, member roles, private content, and moderation controls.
• Federation: ActivityPub support for cross‑instance event discovery, following, and sharing.
• Import/Export APIs: Standard formats (ICS, RSS) for data interchange; a public JSON‑API exposes events, groups, and users.
• Webhooks: Developers can subscribe to event lifecycle hooks (creation, update, deletion) for custom integrations.

Deployment & Infrastructure

Mobilizon is designed to run on a variety of environments. The recommended stack includes:

• Docker: Official images are available, simplifying containerized deployment and scaling.
• Kubernetes: Helm charts provide a declarative way to deploy multiple replicas, manage secrets, and expose services.
• Systemd: For bare‑metal or VMs, the application can be run as a system service.
  The system is horizontally scalable; adding more Phoenix workers or Redis instances boosts throughput, while PostgreSQL can be clustered for high availability.

Integration & Extensibility

Developers can extend Mobilizon in several ways:

• Plugins: The core supports a plugin architecture where additional modules can hook into the request lifecycle or add new routes.
• Custom API endpoints: The Phoenix router allows adding new resources without touching the core codebase.
• Webhooks & Event streams: External services can listen to ActivityPub events or internal webhook callbacks.
• Theme and UI overrides: The React front‑end can be forked or replaced entirely, with a theming system that respects accessibility standards.

Developer Experience

The project offers comprehensive documentation covering architecture, API usage, and deployment. A well‑structured codebase, with clear separation of concerns between contexts (events, groups, users), aids onboarding. The community is active on GitHub and Matrix, providing timely support for issues and feature requests. Licensing under AGPL‑3.0 ensures that any derivative work remains open source, aligning with the platform’s ethos.

Use Cases

• Community event hubs: Local NGOs or hobby groups can run an instance that federates with others, sharing events across the fediverse.
• Corporate training platforms: Internal teams can host a self‑managed instance to schedule workshops, integrating with existing LDAP or SSO systems.
• Educational institutions: Schools can provide a privacy‑first alternative to commercial event tools, with full control over data residency.
• Event aggregators: Developers can build a front‑end that pulls events from multiple Mobilizon instances via the public API, creating a custom discovery layer.

Advantages

• Performance: Elixir/Phoenix’s lightweight processes enable handling thousands of concurrent connections with minimal latency.
• Flexibility: The plugin system and open API allow tailoring the platform to niche workflows without core modifications.
• Federation: Native ActivityPub support eliminates the need for custom data‑exchange layers.
• Open Source & Auditable: AGPL licensing and public source code mean no hidden back‑doors or proprietary features.
• Community & Ecosystem: Active contributors and a growing ecosystem of plugins reduce the maintenance burden for developers.

Mobilizon offers developers a robust, extensible foundation for building privacy‑first event management solutions that can scale from small community sites to federated networks of organizations.