Senior Backend/Fullstack Developer

Are you an experienced .NET Developer who enjoys solving complex technical challenges, improving mature systems, and bringing legacy applications into the modern era?
We're looking for a Senior .NET Developer to join an international technology environment and contribute to the development, modernization, and maintenance of a business-critical digital platform.
This role is particularly suited to someone who combines strong C#/.NET expertise with hands-on PostgreSQL and SQL skills and is comfortable working across both legacy and modern technologies.
What You'll Be Doing:
- Develop, maintain, and continuously improve a business-critical .NET application. - Contribute to the gradual modernization of a legacy .NET platform, while ensuring stability and preserving existing functionality. - Work across both .NET Framework and modern .NET (.NET Core / .NET 6+) environments. - Troubleshoot complex application and database-related issues. - Write, analyze, and optimize raw SQL queries to improve application and database performance. - Identify performance bottlenecks and implement effective technical solutions. - Refactor existing code to improve maintainability, scalability, and overall quality. - Develop and maintain unit and integration tests. - Collaborate closely with other developers and stakeholders while taking ownership of individual technical challenges. - Participate in Agile ceremonies and contribute to continuous improvement across the development lifecycle. - Explore and use AI-assisted development tools to improve productivity, code quality, and problem-solving.
What We're Looking For:
Must-Have Skills:
- Strong professional experience with C# and .NET. - Commercial experience with both: - .NET Framework - Modern .NET (.NET Core / .NET 6+) - Strong hands-on experience with PostgreSQL in production environments. - Excellent knowledge of raw SQL, including: - Complex queries - Query optimization - Performance tuning - Database troubleshooting - Experience maintaining, refactoring, or modernizing legacy applications. - Experience with Git/GitHub and collaborative development workflows. - Hands-on experience with unit and integration testing. - Experience working within Agile/Scrum environments. - Strong troubleshooting and analytical problem-solving capabilities. - Good communication skills and the ability to explain technical topics clearly. - A proactive and independent mindset, with the ability to take ownership of technical challenges.
Nice to Have:
- Experience with CI/CD pipelines, such as Azure DevOps or GitHub Actions. - Experience with Entity Framework or other ORM technologies. - Good understanding of software engineering principles such as SOLID and clean code practices. - Experience with cloud platforms and/or broader DevOps practices. - Hands-on experience incorporating AI-assisted development tools such as GitHub Copilot, Claude Code, Cursor, ChatGPT, or similar into your development workflow.
The Profile We're Looking For:
We're particularly interested in developers who are comfortable working in the space between legacy and modern software engineering.
You should be equally confident navigating an established .NET codebase, investigating a complex PostgreSQL/SQL performance issue, and contributing to the modernization of the application using current .NET practices.
This is a great opportunity for someone who enjoys troubleshooting, modernization, performance optimization, and technical ownership, rather than focusing exclusively on greenfield development.
If you're a strong .NET engineer who enjoys understanding how complex systems really work and improving them step by step, we'd like to hear from you.