Senior .NET Developer

Keystone Solutions is seeking a Senior .NET Developer for a consultancy mission within the Transport Execution Management domain. As a Keystone Solutions consultant embedded with the client, you will design and build high-quality, well-tested software solutions. You will work closely with the client’s solution designer and business stakeholders to translate ideas into effective, reliable applications, gaining a deep understanding of the business context along the way. All responsibilities listed below will be performed under Keystone Solutions’ consultancy model, working in close partnership with the client.

This position is delivered as a Keystone Solutions consultancy mission. You will operate on site at the client’s location as part of an embedded team, aligning with the client’s processes while benefiting from Keystone Solutions’ support network, coaching, and peer community. You will represent Keystone Solutions in daily interactions, bringing our consulting rigor, engineering standards, and values to every deliverable.

We are looking for a senior developer who will take ownership of designing and building high-quality, well-tested software solutions within the Transport Execution Management domain. You will work closely with the solution designer and business stakeholders to translate ideas into effective, reliable applications, gaining a deep understanding of the business context along the way.

Beyond strong technical expertise, we are looking for someone who shows initiative, communicates clearly, contributes actively to the team, and is willing to go the extra mile when needed. You are respectful and calm in your interactions. Independence is key in this role: taking full responsibility for delivering complete solutions is part of your daily work. At the same time, you value teamwork and knowledge sharing. In line with the client’s values, you bring professionalism and a constructive attitude that helps the team move forward.

• For this assignment, the client requires the contractor to agree to be present at the client’s office up to five days per week for the execution of the assignment. The required on-site presence may vary and will be communicated by the client to the contractor during the course of the assignment.
• .NET development: more than 5 years of experience.
• Azure Cloud development: more than 3 years of experience.
• .NET Core Web API development: over 3 years of experience.
• Demonstrable experience in unit testing code on at least 3 projects.
• Demonstrable experience with Clean Code, Clean Architecture and SOLID principles on at least 3 projects.
• You communicate fluently in Dutch or French (spoken and written) at least C2 level.
• You communicate fluently in English (spoken and written) with at least level C1.

• .NET development: demonstrates strong mastery of the .NET ecosystem, including language features, LINQ, async and await, security practices, data structures and design patterns.
• Code quality and craftsmanship: writes clean, maintainable and SOLID code that follows proven engineering practices.
• Web API design and development: designs secure, performant .NET Core Web APIs.
• Azure cloud: leverages Azure services, PaaS components, and event-driven patterns effectively.
• Unit testing and test quality: creates meaningful, maintainable and automated unit tests.
• CI/CD and DevOps practices: sets up robust Azure DevOps pipelines and manages containerized deployments with Kubernetes and Docker.
• API integration and offline and online synchronization: integrates reliably with backend APIs and designs Android applications that can handle offline usage, local persistence, synchronization, conflict handling and recovery when connectivity is restored.
• SQL and database design: models, queries, and optimizes relational databases.
• Git and version control: applies branching strategies and collaborates efficiently using Git.
• Communication: explains technical choices clearly.

As a Keystone Solutions consultant, you will tackle complex challenges in transport and logistics while gaining exposure to adjacent domains. You will contribute to modernizing platforms, building resilient APIs, applying event-driven patterns on Azure, and improving offline capable mobile solutions. Future missions can extend to different clients and industries, giving you variety without sacrificing impact.

We invest in your growth through certification support, coaching by senior architects, hands-on communities of practice, and access to curated learning paths covering .NET, Azure, DevOps, and cloud-native architectures. You will have opportunities to present lessons learned, pair with peers, and apply modern engineering practices on real projects.

Keystone Solutions provides a clear progression path for consultants who take ownership, deliver quality, and mentor others. You can broaden your impact across multiple client engagements, shape engineering standards, and evolve toward solution design, technical leadership, or architecture, all while maintaining strong ties to hands-on delivery.

Being a K-Stone means you show ownership, curiosity, craftsmanship, and teamwork on every engagement. We uphold clarity in communication, respect in collaboration, and a commitment to delivering business value. You will bring these values to the client site daily, ensuring high standards and a constructive partnership.

• Apply Clean Architecture, SOLID, and test-first practices across multiple client scenarios, from greenfield APIs to modernization of existing systems.
• Design resilient, secure Web APIs on .NET Core, integrate with Azure PaaS, and implement event-driven patterns that scale.
• Contribute to CI/CD pipelines with Azure DevOps and containerized workloads on Kubernetes and Docker, improving delivery speed and reliability.
• Support mobile and edge use cases by enabling offline and online synchronization and robust recovery strategies.
• Leverage deep knowledge of relational databases to optimize performance and reliability in production.
• Mentor peers, share knowledge, and represent Keystone Solutions’ engineering excellence on site with the client.

If you are ready to tackle technical and strategic challenges in a dynamic consultancy environment, apply today at Keystone Solutions Career Portal.