[Hiring] Senior .NET Developer @Deutsche Telekom

Role Description

The Project:

Internal Support Tools Evolution

You are joining an initiative focused on the evolution, modernization of the Internal Application Landscape. This project involves the strategic transition of well-known cloud services and legacy .NET architectures into a next-generation, AI-augmented, and cloud-native software landscape.

Our goal is not simply to "maintain" the existing system, but to proactively transform it—ensuring sovereignty, high-performance scalability, and seamless handover readiness through disciplined engineering.

Our Engineering Philosophy

• AI-Augmented Engineering: We utilize advanced AI development environments (such as Cursor, Windsurf, and Claude Code) and cutting-edge model families to accelerate code comprehension, refactoring, and documentation.
• Disciplined SDLC Patterns: We move beyond traditional development by implementing repeatable, evidence-based SDLC patterns. Every change is backed by structured engineering evidence and rigorous automated testing.
• The "Strangler Fig" Modernization: We prioritize risk-mitigated evolution, using sophisticated patterns to wrap, refactor, and eventually replace legacy components.
• High-Seniority Autonomy: We operate as a lean, highly autonomous unit. We value "technical detectives" who can navigate ambiguity and perform deep reverse engineering.

Mission

To drive the technical execution of both high-impact feature development and the deep-dive modernization of our legacy .NET ecosystem. You will be a specialist who finds satisfaction in solving complex puzzles, utilizing AI-assisted tools to accelerate the modernization of our core systems.

Role Focus

This role focuses on high-complexity coding, deep reverse engineering, and AI-augmented productivity. You will work in the trenches of the legacy codebase, extracting logic and implementing modern, testable solutions using the latest AI-powered development environments.

Qualifications

• Experience: 6+ years of professional software development experience, with deep expertise in the .NET/C# stack.
• Legacy Navigation: Proven experience working with older .NET versions (e.g., .NET Framework) and managing the complexities of monolithic architectures.
• AI Tooling Proficiency: Hands-on familiarity with AI coding assistants, prompt engineering, or local model experimentation.
• Core Skills: Mastery of SOLID principles, design patterns, and advanced debugging/profiling techniques.
• Testing Mindset: Strong commitment to TDD and automated testing (Unit/Integration) to protect the legacy core.

Requirements

• Complex Feature & Refactoring: Design and implement sophisticated new functionalities within the existing .NET ecosystem, ensuring seamless integration with legacy components.
• Deep Reverse Engineering: Analyze and deconstruct complex, undocumented, or "spaghetti" legacy code to understand underlying business rules and technical flows.
• AI-Augmented Coding: Proactively utilize AI coding assistants and advanced environments (e.g., Cursor, Windsurf, Claude Code, or VS Code extensions) to accelerate code comprehension, documentation, and refactoring.
• Robust Testing & Stability: Write high-quality unit and integration tests to "wrap" legacy modules, providing a safety net for all refactoring efforts.
• Technical Troubleshooting: Act as a high-level escalation point for complex bugs and performance bottlenecks within the legacy environment.
• Internal Tooling: Utilize Microsoft PowerApps to build rapid, lightweight administrative or maintenance utilities to support the development and operations lifecycle.

Benefits

• Please be informed that our remote working possibility is only available within Hungary due to European taxation regulation.