Required skills
Job description
Project overview
For one of our clients, an international software vendor in the construction industry, we are looking for an experienced Senior .NET Engineer (m/f/x) to support the modernization of a large C#/.NET application.
The project involves migrating a complex legacy environment with over 1,600 backend projects into modern services and APIs on Azure. You’ll work in a focused engineering team alongside a security engineer, with clear milestones, measurable results and close collaboration with the client’s senior developers.
Your Profile and Responsibilities
›› Modernization of a large legacy C#/.NET application into scalable services and APIs on Azure
›› Hands-on development, migration and optimization of backend services and Angular applications
›› Close collaboration with security engineers to ensure secure architectures and implementations
›› Performance optimization, automated testing and continuous improvement of application quality
›› Knowledge transfer through pair programming, workshops and mentoring of internal engineers
Mandatory Requirements (Evidence Required: What, When & at What Scale)
All must-haves must be supported by at least one concrete project example (what, when and at what scale) for your application to be considered.
›› Converted a legacy C# application into services and APIs on a real production system
›› Upgraded a product from .NET Framework 4.8 or .NET Core 3.1 to modern .NET (8 or later), including dependency updates, IIS hosting impact and automated regression testing
›› EF Core read/write patterns and SQL Server performance tuning
›› Redis caching (StackExchange.Redis) with measured performance results
›› Full-stack: C# plus Angular, including migration off AngularJS
›› Uses AI-assisted and agentic development tools daily, while reviewing and owning the output
›› Proven knowledge transfer: pair or mob programming, workshops, mentoring, writing runbooks
Nice-to-Haves
›› IIS hosting, memory management and scaling on Azure VMs
›› Observability: Datadog, Azure Application Insights, NLog
›› Azure DevOps Pipelines and SonarQube quality gates
›› Strangler Fig pattern and contract-first OpenAPI design
›› Nx monorepo experience
›› Secure coding basics (OWASP Top 10, working with OAuth 2.0 / OIDC)
Project details
›› Start: ASAP
›› Duration: 6 months
›› Workload: Full-time (1 FTE)
›› Location: Remote, ideally with 1–2 on-site visits in Germany during the assignment
Please include your English CV, concrete project examples for each mandatory requirement, availability, hourly rate and location when applying.
If you’re interested, feel free to apply through our project portal: CONNECTLY de/jobs/c-net-developer-m-w-x-231/
We’d also be happy to connect with you on LinkedIn!
Best regards,
Marcel Wlömer
- Start: ab sofort
- Duration: 6 Monate
- Remote: remote
- Location: köln, Deutschland, DE
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