Senior .NET Developer / Architect

In Goelett, we are an extraordinary mix of travel industry experts, product, and software engineers, developing a successful online booking tool for corporations and large organizations. Today, as a part of the sector leader S4BT Group, we support 500k+ business users making thousands of bookings a day. We are seeking a Senior.Net Developer / Architect who is keen on working within a product development team, has a background in system and integration analysis, and is ready to take on a dynamic career opportunity by driving requirements analysis, resolving system issues, and enhancing product functionalities! Work model: hybrid (3 days in the office + 2 days remote / weekly) – office located in Warsaw, PL. What you will be doing: Develop clean, scalable code using C# / .NET in a microservices, cloud-native architecture (Azure/AWS). Design and implement high-performance travel search and booking flows (shopping, pricing, availability, ticketing). Integrate with GDS, NDC, LCC APIs. Work with flight and ancillary services including seat maps, baggage, fare families, upsell/cross-sell. Optimize search performance (latency, caching strategies, concurrency, rate limiting, resiliency patterns). Implement orchestration layers for multi-provider search aggregation and normalization of responses. Handle complex pricing logic (fare rules, combinability, branded fares, dynamic pricing). Monitor and optimize system performance, observability (logging, tracing, metrics), and reliability (SLAs/SLOs). Build and maintain scalable APIs (REST/SOAP), event-driven components, and asynchronous workflows. Ensure high availability and fault tolerance in distributed systems (circuit breakers, retries, fallbacks). What we're looking for: 5+ years of professional experience in software development using C# / .NET and modern cloud architectures. 5+ years of travel experience in travel business: flight shopping, booking engines, OTA platforms, or metasearch. Hands-on experience integrating with GDS (Sabre, Amadeus, Travelport) and/or NDC APIs. Solid understanding of airline concepts: PNR, e-ticketing, fare rules, availability, schedule changes, cancellations. Experience with high-throughput, low-latency systems and distributed architectures. Experience with observability tools (e.g., OpenTelemetry, Application Insights, Grafana). Ability to translate business requirements (conversion, pricing accuracy, availability) into technical solutions. What we offer: A truly global perspective – develop your international mindset by collaborating daily with colleagues from diverse cultures and backgrounds across the world. Real impact – contribute to shaping the future of one of the most user-centric companies in the travel-tech industry. Your ideas and solutions will reach thousands of users globally. Medical care – because your well-being matters. Multisport card – keep your body as active as your mind. Extra days off – celebrate your day with a paid day off for your birthday, and another to give back through volunteering. Language courses – grow your communication skills and connect effortlessly in our multicultural environment. Team integrations & fun events. Lunch vouchers – enjoy your breaks with tasty meals on us.