Senior Backend Engineer – Mobile

Sunweb Group; Rotterdam; Hybrid; EUR 60,000 - 73,000; Full time

Benefits offered by this job

Hybrid work model

Rotterdam office

Travel allowances

Equipment provided

Career development plan

Coaching sessions

Work-from-home allowances

Job summary

Sunweb Group is seeking a Senior Backend Engineer – Mobile to own the backend services behind our native apps. You will design, build and run REST APIs and cloud-native .NET services used by Sunweb Group apps, shielding mobile clients from travel-domain complexity.

Based in the Rotterdam area with flexible hybrid work, you will collaborate with mobile engineers, product owners and architects, mentor teammates, and raise the bar on testing, CI/CD, observability and security.

Qualifications

• Minimum 5 years backend experience with modern C# and .NET.
• Design REST APIs for mobile clients with versioning and backward compatibility.
• Model complex travel-domain data (bookings, customers, payments).
• Strong knowledge of cloud-native architectures on Azure.
• Fluent English and strong stakeholder communication.

Responsibilities

• Design, build and operate cloud-native .NET services and REST APIs on Azure.
• Own critical mobile-backend capabilities end to end.
• Define and enforce testing, CI/CD, observability and security standards.
• Collaborate with mobile engineers, product owners and architects.
• Mentor teammates and shape backend practices in a mobile-first team.
• Ensure backward compatibility across app versions.

Skills

5+ years C#/.NET

REST API design

API versioning

Domain modelling

Azure cloud

SQL modelling

CI/CD & tests

Production monitoring

English proficiency

Stakeholder communication

Ownership & go-to backend

Tools

Azure

Cosmos DB

Service Bus

New Relic

GitHub Actions

Azure Functions

Job description

Own the services behind our native apps—and shape the role as you go

Our native apps depend on stable, fast and thoughtfully designed services.

As our Senior Backend Engineer – Mobile, you will become the dedicated backend engineer in Team Cuba. You will design, build and run the APIs and services used by the Sunweb Group apps.

You will also shield our mobile clients from the complexity of travel domains, internal services and third-party integrations.

Location: Girona preferred / Rotterdam possible
Way of working: Flexible hybrid
Contract: Full-time
Team: Team Cuba – Mobile

Your impact

• Design, build and operate cloud-native .NET services and REST APIs on Azure.

• Create stable, versioned and backwards-compatible contracts, as older app versions can remain in use for several months.

• Own critical mobile-backend capabilities end to end.

• Develop services covering app configuration, feature toggles, push notifications and mobile BFF functionality.

• Model complex travel domains such as bookings, customer information, excursions, transfers and payments.

• Integrate with other Sunweb product teams and external partners while keeping complexity away from the mobile clients.

• Raise standards for testing, CI/CD, observability, security, performance and documentation.

• Take ownership from technical design through deployment, monitoring and production support.

• Collaborate directly with mobile native engineers, the Product Owner, Engineering Lead, architects and platform specialists.

• Mentor mobile engineers on backend and API topics.

• Help define how backend engineering works within a mobile-first team.

What about the team?

Within Team Cuba wou will be the only dedicated backend engineer within the team.

That means genuine autonomy and visible influence—but also responsibility. You will not inherit a finished playbook; you will help create it.

The team is growing to seven colleagues across Girona and Rotterdam. Clear technical judgement, ownership and proactive written communication are therefore essential.

Our tech stack

C# · Modern .NET · Microsoft Azure · REST APIs · SQL · GitHub Actions · CI/CD · New Relic · Azure App Service · Azure Functions · Service Bus · Cosmos DB · Redis · Clean Architecture · DevOps

What you bring

• Strong professional experience (5+) with modern C# and .NET.

• A track record of designing REST APIs for external or mobile clients.

• Experience with API versioning and backwards compatibility.

• Practical domain-modelling and clean-architecture experience.

• Sound judgement about boundaries and where business logic belongs.

• Cloud-native experience on Azure—or comparable cloud experience with the motivation to specialise in Azure.

• Strong SQL and data-modelling skills.

• Automated unit and integration testing as standard engineering practices.

• Experience with CI/CD and production monitoring.

• A good understanding of performance, scalability and security.

• You move decisions forward and get things into production.

• Professional working proficiency in English.

• Strong stakeholder-communication skills.

• The confidence and ownership required to become the backend go-to person.

Nice to have

• Experience building backends for mobile applications.

• Experience with BFF patterns, push notifications, remote configuration or feature toggles.

• Third-party integration experience, especially with payment services.

• Event-driven architecture and messaging, such as Azure Service Bus.

• Experience in high-traffic consumer, e-commerce or travel domains.

• Spanish, Catalan or Dutch language skills.

Why join our journey?

• Take end-to-end ownership of the entire mobile-backend surface.

• Have substantial influence over its technical direction.

• Establish engineering practices in a newly created, mobile-first backend role.

• Work on meaningful API-design challenges where stability and backwards compatibility genuinely matter.

• Collaborate directly with mobile engineers, product specialists and architects.

• Help shape digital holiday experiences used by customers across Europe.

What we offer

For a Dutch contract (based in our Rotterdam office):

• Monthly gross salary between €5400 and €6500 plus 6 ATV days (based on full-time employment, excluding 8% holiday allowance). Please note: ATV days do not apply to part-time contracts.

• We enjoy the journey so enjoy 25 holidays based on fulltime employment.

For a Spanish contract (based in our Girona office):

• Yearly gross salary between €56.000,- and €71.000- (based on full-time employment)

• We enjoy the journey so enjoy 23 holidays based on fulltime employment.

The final offer depends on your experience and local employment contract.

Additionally, we offer:

• Enjoy up to 20% off when booking with our brands for you, your family, and your friends.

• As an international company we support a hybrid way of working. We provide you with office furniture and IT equipment.

• A personalized Reflect & Develop Plan to support your career growth.

• Benefit from coaching sessions designed to support your well-being.

• Receive work-from-home and travel allowances to ease your daily routine.

Ready for departure?

Do you want to join Team Cuba as our Senior Backend Engineer – Mobile?

Do you have any questions? Please feel free to reach out to our Talent Acquisition team via [e-mail]. We are looking forward to hearing from you!

Application deadline: 31 October

Sunweb Group is an equal opportunity employer, which means we do not discriminate in any way. We celebrate diversity and are committed to creating an inclusive and safe environment for all employees.

As part of our recruitment process, we use AI-supported tools to assist recruiters in matching candidates to job requirements. Final hiring decisions are always made by human recruiters.