Senior Software Engineer | Duffel

Duffel, one of Europe’s most exciting travel technology companies, is hiring a Senior Software Engineer in London, United Kingdom, for 2026, with Skilled Worker visa sponsorship available for qualified international candidates. This is a rare opportunity to join a fast-growing, venture-backed company that is rebuilding the core infrastructure of the global travel industry and powering millions of bookings through a single, modern API.

Based in London with a hybrid working model, this role is ideal for experienced engineers who want to work on globally impactful systems, solve complex integration problems at scale, and help define the technical standards of a high-growth product company. You will be working on mission-critical systems used by travel companies worldwide while enjoying the stability, benefits, and long-term career growth that come with a well-funded, product-led technology firm.

As a Senior Software Engineer at Duffel, you will play a key role in designing, building, and scaling the core APIs and backend systems that connect hundreds of airlines and travel providers into a single unified platform. The work focuses on building elegant, reliable, and developer-friendly systems in a highly distributed and complex ecosystem.

While Duffel’s stack includes Elixir, Phoenix, Kubernetes, and Google Cloud, the company prioritizes strong engineering fundamentals, system design skills, and product thinking over specific language experience. This is a high-impact role with real influence over architecture, standards, and long-term technical direction.

Duffel is a Y Combinator-backed travel technology company supported by leading investors, including Benchmark, Blossom, Index Ventures, and Kima Ventures. The company is on a mission to modernise global travel distribution and eliminate the complexity behind flight and travel bookings.

Headquartered in London, Duffel serves customers worldwide and offers a highly international, product-focused, and engineering-driven culture. The company actively supports international hires through UK Skilled Worker visa sponsorship and relocation support.

• Design, build, and maintain scalable APIs that power global travel search and booking
• Develop robust backend systems integrating with hundreds of external travel providers
• Improve reliability, performance, and developer experience of Duffel’s core platform
• Contribute to architectural decisions and long-term technical strategy
• Write high-quality, maintainable, and well-tested production code
• Collaborate closely with product, design, and other engineers to deliver impactful features
• Help define engineering standards, best practices, and development processes
• Participate in code reviews, technical discussions, and system design sessions

• Strong experience as a Software Engineer working on backend or platform systems
• Proven ability to design and maintain APIs and distributed systems
• Excellent software engineering fundamentals and code quality standards
• Experience working with cloud infrastructure and modern deployment practices
• Strong communication skills and ability to work in collaborative product teams
• Product-minded approach and ability to balance technical and business priorities
• Experience with high-scale or integration-heavy systems is a strong advantage
• Eligible for UK Skilled Worker visa sponsorship

This is a standout Senior Software Engineer job in the UK in 2026 with visa sponsorship, offering international candidates the chance to work on globally impactful technology, earn equity, and build a long-term career in one of Europe’s most ambitious travel tech companies. For engineers seeking scale, ownership, and real-world impact, Duffel represents an exceptional opportunity.