Alf.io

Alf.io is a self‑hosted, open‑source ticket reservation and event attendance platform written in Java 17. It is built on the Spring Boot ecosystem, leveraging Gradle for build automation and PostgreSQL 10+ as its primary data store. The application is modular, exposing a rich REST API for ticket sales, event management, and reporting, while also providing an optional web‑based backoffice UI and a mobile check‑in client. Its architecture is designed around micro‑service friendly patterns—stateless HTTP endpoints, database session persistence via a dedicated jdbc-session profile, and pluggable extensions for payment providers (Stripe, Mollie, PayPal, etc.) and external systems such as CRMs.

Key Features

• Event lifecycle management – Create events, define ticket types, set pricing rules, and enforce seat allocation.
• Secure payment integration – Built‑in adapters for major processors; all sensitive data is handled via encrypted channels and row‑level security in PostgreSQL.
• Extensible extension framework – Developers can add custom logic through Spring Boot starters, or integrate with third‑party services using webhooks and the public API.
• Offline check‑in – The Alf.io‑PI component runs on Raspberry Pi, clustering with the central instance to download an encrypted attendee list and perform high‑throughput badge printing.
• Multi‑tenant support – Each event is isolated via database schemas and row‑level security, enabling a single deployment to serve many organizers.

Technical Stack

Core Capabilities for Developers

• REST API – CRUD operations for events, tickets, orders; authentication via JWT or session cookies. Endpoints are documented in OpenAPI format and can be consumed by custom front‑ends or third‑party services.
• Webhooks – Subscribe to order status changes, payment events, and check‑in completions; payloads are signed for integrity.
• Extension Points – Implement custom PaymentProvider or EventValidator beans; register them via Spring’s component scanning.
• CLI Tools – The alfio-cli module offers command‑line utilities for bulk imports, data migration, and health checks.
• Row‑Level Security – Developers can define fine‑grained access policies directly in SQL; the application automatically enforces them via SET ROLE statements.

Deployment & Infrastructure

• Self‑hosting – Requires a JDK 17 runtime and PostgreSQL; no external services are mandatory.
• Scalability – Stateless HTTP layer allows horizontal scaling behind a load balancer; database can be read‑replicated for high traffic scenarios.
• Container Support – Docker image exposes JAVA_OPTS and SPRING_PROFILES_ACTIVE; Kubernetes Helm charts are available in the community repository.
• High Availability – The jdbc-session profile persists user sessions, enabling seamless failover; the PI component clusters automatically on first boot.

Integration & Extensibility

• Payment Gateways – Out‑of‑the‑box adapters for Stripe, Mollie, PayPal, Revolut; each implements a common PaymentService interface.
• CRM / ERP Hooks – Use webhooks to push attendee data into external systems; alternatively, consume the API from a custom connector.
• Custom UI – The front‑end is built with Thymeleaf; developers can override templates or replace the entire UI with a SPA that consumes the API.
• SDKs – While not bundled, community libraries exist for Node.js, Python, and Go to interact with the REST API.

Developer Experience

• Configuration – All settings are externalized via application.yml; environment variables can override properties, making CI/CD pipelines straightforward.
• Documentation – The GitHub repo contains a comprehensive README, API reference, and contribution guidelines; the CI pipeline publishes coverage and security metrics.
• Community – Active issue tracker, open pull requests, and a dedicated Discord channel provide quick support; contributors are recognized via Open Collective sponsorship.
• Licensing – GPLv3 ensures freedom to modify and redistribute, with a clear dual‑licensing path for commercial use.

Use Cases

Advantages Over Alternatives

• Performance – Spring Boot’s embedded server and JPA with PostgreSQL RLS provide low latency for ticket purchases.
• Flexibility – Complete source code