Senior .NET Developer (ZZP)

What We Do

Utilus is a fast-growing and highly ambitious software delivery company. We design, build, manage and operate highly scalable and complex software projects in the heart of the primary business processes of our clients, including Tennet, Eneco, Dura Vermeer and Nederlandse Loterij.

We work on sustainability by focusing mainly on assignments in the heart of the energy transition. We believe in the universal truth that true transformation is only attainable if our clients are prepared to ‘do the work’. That’s why at Utilus, we help our clients to ‘do the work’: by developing an approach to improve and renew essential IT, all while keeping the clients business running smoothly.

We take an honest and constructive approach, our two core values, to renewing and enhancing essential IT systems.

About The Job

The Senior .NET Developer is responsible for designing, developing, and deploying high-value, high-performance backend services. The engineer will work with modern .NET technologies to build scalable APIs and services, enabling improved efficiency, compliance, and scalability across the energy ecosystem.

Key Responsibilities Senior .NET Developer

• Refine functionalities with end users or stakeholders.

• Design and implement the technical solution in the ecosystem of scalable services and APIs using ASP.NET Core.

• Design and suggest architecture patterns, and defend them with logical, documented reasoning.

• Construct software systems from scratch in an observable,  stable, scalable, and maintainable manner.

• Handle the life cycle of the deliverables. CI/CD pipelines, build, containerize, and deploy to a Kubernetes cluster (usually).

• Troubleshoot production and development issues to ensure timely resolution and propose/implement a structural fix for the future

What We Are Looking For

• Bachelor's/Master degree in IT (or related) field

• Strong C#/.NET Core development experience (5–8 years)

• Proficiency in ASP.NET Core for building scalable APIs and microservices.

• Experience with containerization and Kubernetes deployments.

• Strong problem-solving abilities and attention to detail.

• Effective communication and cross-team collaboration.

• Ability to adapt quickly in fast-changing, ambiguous environments and domains.

Nice-to-Have:

• Experience with Microsoft Azure services

• Solid understanding of SQL

• Experience in the energy industry

What We Offer

• Challenging project in the energy sector 

• Start date: July 1, 2026

• Work week: 40 hours 

• Duration of the project: October 31, 2026

• Location: Hybrid (office in Rotterdam)

*Please note that we only accept applicants that are located in the Netherlands at time of application