Pretix powers thousands of events and millions of ticket sales through a fully brandable ticket shop with interactive seating plans, 30+ payment providers, and a mobile check-in app for venue entry management. With over 2,400 GitHub stars, it delivers what organizations need when they demand full control over attendee data and revenue rather than surrendering margins to Eventbrite or Ticket Tailor. Built with Python and Django on PostgreSQL with Redis and Celery, the ticket shop adapts to your colors, logo, and domain with responsive design. The graphical seating plan editor handles everything from small cinemas to large stadiums, letting buyers choose seats mapped to pricing categories. Payment providers connect through plugins including Stripe, PayPal, Mollie for iDEAL and Bancontact, SEPA direct debit, and bank transfer with automatic CSV import for payment matching. The voucher engine generates bulk discount codes with usage limits, quota reservations, and automated email distribution. Waiting lists automatically offer released tickets to the next registrant with expiration deadlines. A built-in mini-CMS hosts event descriptions, terms of service, and static pages directly in the ticket shop. Customer accounts enable repeat buyers to check out faster across events. The pretixSCAN mobile app performs QR code check-in on Android and iOS with offline capability. Embeddable JavaScript widgets integrate the shop into any website. Plugin architecture extends functionality with output formats, analytics, and Apple Wallet passes. Deploy via Docker with the pretix/standalone image alongside PostgreSQL and Redis. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Alf.io handles the complete conference and event lifecycle from ticket distribution through check-in to financial reporting, built for organizers who refuse to surrender attendee data to third-party ticketing platforms like Eventbrite or Tito. Built on Java 17 with Spring Boot and PostgreSQL with row-level security policies, the project has earned over 1,500 GitHub stars from privacy-conscious event organizers across Europe and beyond. Payment processing supports Stripe for credit cards, Mollie for iDEAL, Bancontact, KBC/CBC, and Przelewy24, plus Revolut, PayPal, bank transfers, on-site collection, and configurable custom offline payment methods with localized instructions. Multi-tier ticket categories enable early bird, VIP, standard, and free registrations with promotional codes, group discounts, and waiting lists that automatically notify next-in-queue when cancellations occur. Customizable registration forms collect attendee data beyond standard fields, while EU VAT management validates tax IDs through the VIES web service and supports Italian e-invoicing with automatic PDF invoice generation attached to confirmation emails. The Alf.io Scan mobile app for iOS and Android performs QR code check-in at venue entrances, and the Alf.io-PI project provides Raspberry Pi-powered offline-capable check-in stations that form encrypted clusters for high-throughput badge printing at large events. Apple Wallet integration delivers digital passes via PassKit. The extensions system integrates with CRMs, accounting platforms, Slack, Telegram, and Mailjet. Multi-language support covers nine languages. Deploy via Docker with PostgreSQL. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPLv3 licensed.