SkyWings: Building an Airline Reservation System from Scratch

SkyWings is a full-stack airline booking platform that I built to explore the complexities of transaction processing, seat inventory management, and document generation. Building an airline reservation system from scratch is a humbling experience because it forces you to confront every edge case in transaction processing. Double-booking is simply not an option, and the system must handle concurrent requests from multiple users trying to book the same seats simultaneously.

The heart of the system is the database schema. I used PostgreSQL with Supabase, which provides Row Level Security and database triggers that enforce business rules at the data layer rather than relying on application code to behave correctly. The seating system uses a combination of explicit row-level locks and optimistic concurrency control. When a user begins the booking flow, the selected seats are temporarily held with a configurable timeout. If the booking is not completed within that window, the seats are automatically released. This prevents users from blocking seats indefinitely while they decide.

The seat selection interface was one of the most interesting UI challenges. An airplane seat map is a complex grid with irregular geometry. Aisles split the cabin, some rows have missing seats, and exit rows have different spacing. I built a data-driven seat map renderer that takes a configuration object describing the aircraft layout and generates the interactive map dynamically. This means the same component can render a Boeing 737, an Airbus A320, or any other configuration without code changes.

PDF boarding pass generation was another technically interesting component. When a booking is confirmed, the system generates a PDF boarding pass with a unique QR code, passenger details, flight information, and seat assignment. I used a server-side PDF generation library that takes structured data and produces a print-ready document. The QR code encodes the booking reference and a cryptographic signature that can be verified at the gate.

The flight search functionality required careful indexing and query optimization. Users search by origin, destination, date, and passenger count. The database needs to find available flights, check seat availability across multiple fare classes, and return results quickly. I created composite indexes on the most common query patterns and used database views to precompute availability summaries.

Building SkyWings taught me about the importance of transactional integrity in a system where money and customer experience are at stake. A booking system cannot afford to be eventually consistent. It must be strongly consistent, because the cost of a double-booking error is not just a technical bug but a real customer who shows up at the airport with no seat. I implemented comprehensive integration tests that simulate concurrent booking attempts and verify that the system maintains correctness under load. These tests caught several subtle race conditions that would have been extremely difficult to debug in production.