Senior Backend Engineer – Mobile

As Senior Backend Engineer – Mobile, you own the mobile-backend services and APIs that power Sunweb Group’s native apps. You design, build, and operate cloud-native .NET services on Azure, ensuring stable, versioned contracts and end-to-end ownership of mobile-backend capabilities. You collaborate across cross-functional teams to simplify the mobile client experience and drive testing, observability, security, and performance standards. This is a mobile-first role with high impact on travel-domain systems and partner integrations.

• hybrid work
• office furniture and IT equipment
• 25 holidays (full-time)
• travel and work-from-home allowances
• Reflect & Develop Plan for career growth
• coaching sessions for wellbeing

• Design, build and operate cloud-native .NET services and REST APIs on Azure
• Maintain stable, versioned contracts compatible with older app versions
• Own critical mobile-backend capabilities end-to-end (configuration, feature toggles, push notifications, mobile BFF)
• Model complex travel domains (bookings, customer data, excursions, transfers, payments)
• Integrate with Sunweb product teams and external partners to shield mobile clients from complexity
• Raise standards for testing, CI/CD, observability, security, performance and documentation
• Collaborate with mobile engineers, Product Owner, Engineering Lead, architects and platform specialists
• Mentor mobile engineers on backend and API topics
• Help define backend engineering practices within a mobile-first team
• Take ownership from technical design to deployment, monitoring and production support

• 5+ years of experience with modern C# and .NET
• Proven REST API design experience for external or mobile clients
• Experience with API versioning and backward compatibility
• Domain modelling and clean-architecture expertise
• Cloud experience on Azure (or willingness to specialise)
• Strong SQL and data-modelling skills
• Automated unit and integration testing
• CI/CD and production monitoring experience
• Understanding of performance, scalability and security
• Proactive, production-ready decision-making and ownership
• Professional English with strong stakeholder-communication skills
• Ability to be the backend go-to person in a mobile-first team

• Strong stakeholder communication
• Ownership and proactive writing
• Collaboration with cross-functional teams
• Azure (App Service, Functions, Service Bus, Cosmos DB)
• REST APIs, API versioning, Backwards compatibility
• C# / .NET (modern)