About the job

Duffel is rebuilding the infrastructure that underpins global travel, modernising airline and travel distribution, search, and booking through a single, developer-first API used by millions of travellers worldwide. As a Backend Software Engineer in London, you will work on core backend systems that integrate with hundreds of travel providers, each with different legacy systems and requirements, while delivering a reliable, scalable, and elegant developer experience. You will help design and build beautiful APIs, maintain high standards for code quality and system design, and contribute to defining engineering processes and best practices as Duffel scales. The role values strong engineering fundamentals over specific language experience, with the current stack including Elixir, Phoenix, Kubernetes, and Google Cloud Platform. You will collaborate closely with other engineers in a hybrid environment, balancing technical trade-offs with real business impact, and communicating clearly about what you’re building and why. Duffel offers a competitive salary and equity, work-from-anywhere flexibility, a travel allowance to use the product you help build, matched parental leave, a fully paid three-month sabbatical programme, visa sponsorship, and a Shoreditch office with regular team socials. This is a high-impact opportunity at a YC S18-backed startup supported by Benchmark, Index Ventures, Blossom, and Kima Ventures, where early ownership directly shapes the future of travel technology.