Xamarin Developer

Mission Overview:

Join Keystone Solutions as a senior .NET for Android consultant to deliver a consultancy mission for our client within the Transport Execution Management domain. As a Keystone Solutions consultant, you will take ownership of designing and building high-quality, well-tested software solutions, working closely with the client?s solution designer and business stakeholders to translate ideas into effective, reliable applications while gaining a deep understanding of the business context.

Beyond strong technical expertise, you demonstrate initiative, clear communication, active team contribution, and a willingness to go the extra mile when needed. You are respectful and calm in your interactions. Independence is key: taking full responsibility for delivering complete solutions is part of your daily work. At the same time, you value teamwork and knowledge sharing. Aligned with strong professional values, you bring professionalism and a constructive attitude that helps the team move forward.

Consultancy Model at Keystone Solutions:

This is a consultancy role where you will work on-site with the client as part of Keystone Solutions? engagement. You will collaborate with client teams, adapt to their environment and standards, and deliver outcomes under Keystone Solutions? high-quality consulting framework.

Key Responsibilities and Impact:

• Design and build high-quality, well-tested software solutions within the Transport Execution Management domain as a Keystone Solutions consultant for our client.
• Work closely with the client?s solution designer and business stakeholders to translate ideas into effective, reliable applications.
• Gain a deep understanding of the business context while delivering robust, maintainable solutions.
• Show initiative, communicate clearly, contribute actively to the team, and be willing to go the extra mile when needed.
• Demonstrate respect and calm in interactions, taking full responsibility for delivering complete solutions.
• Value teamwork and knowledge sharing, bringing professionalism and a constructive attitude that helps the team move forward.

Conformity Criteria:

• .NET development: more than 5 years of experience
• .NET for Android / Xamarin.Android: more than 3 years of experience. Experience limited to cross-platform UI frameworks such as Xamarin.Forms or .NET MAUI does not count.
• Demonstrable hands-on experience with MvvmCross
• Experienced in unit testing code
• Demonstrable experience with Clean Code, Clean Architecture and SOLID principles
• CI/CD: experience implementing and managing pipelines using Microsoft Azure DevOps
• Minimum 2 days onsite in Brussels
• You communicate fluently in English and Dutch or English and French (spoken and written). Dutch or French as a mother tongue or at least C2 level. For English at least level C1

Evaluation Criteria:

• .NET development ? demonstrates strong mastery of the .NET ecosystem, including language features, LINQ, async/await, security practices, data structures and design patterns.
• Android development ? understands Android UI layouts, components, responsive/adaptive design and native platform integration.
• Android internals ? understands activity/fragment lifecycle, services, background work, push notifications, WorkManager and native SDK behavior.
• MvvmCross ? understands navigation, view model lifecycle, bindings, dependency injection and platform-specific integration.
• Code quality & craftsmanship ? writes clean, maintainable and SOLID code that follows proven engineering practices.
• Unit testing & test quality ? creates meaningful, maintainable and automated unit tests.
• CI/CD & DevOps practices ? sets up robust Azure DevOps pipelines for building, testing and releasing software.
• API integration & offline/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.
• Git & version control ? applies branching strategies and collaborates efficiently using Git.
• Collaboration & communication ? explains technical choices clearly, works constructively in a team and remains professional under pressure.

Consultancy Advantages at Keystone Solutions:

• Consultancy nature of work: Operate as a Keystone Solutions consultant, working on-site at client locations, collaborating closely with stakeholders while benefiting from Keystone?s delivery standards and support.
• Dynamic projects: Tackle diverse challenges across various client engagements, applying your Android and .NET expertise in multiple domains and contexts.
• Turbo-charged learning and development: Access broad learning opportunities, peer knowledge sharing, and professional development support to elevate your craft continuously.
• Ambition skyrocketing within a consultancy framework: Grow your career through varied, impactful client missions that expand your leadership, architectural, and delivery responsibilities.

Values at Keystone Solutions:

As a K-Stone, you bring professionalism, clarity, collaboration, and ownership to every client project. Our core values shape how we engage, deliver, and continuously improve, ensuring constructive teamwork, knowledge sharing, and reliable outcomes for our clients.

Location and Language:

• Minimum 2 days onsite in Brussels at the client location.
• Language requirements: Fluency in English and Dutch or English and French (spoken and written). Dutch or French at least C2 level; English at least C1.

How to Apply:

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