Backend Engineer
Senior Software Engineer – C#/.NET
Warsawcontractsenior
Apply on the employer's siteRole description
Location: Warsaw, Poland (Hybrid, 2–3 days per week onsite)
UoP/b2b
About the Role
For our client we are looking for a Senior Software Engineer to join a product engineering team developing enterprise-grade software used by organizations worldwide. This is a backend-focused role where you will design, build, and enhance complex product capabilities that support administration, automation, reporting, and system management workflows.
You will work on a mature, commercially successful product while contributing to its ongoing evolution. A significant part of the work involves building new functionality, improving scalability and reliability, and helping modernize selected components into a modern C#/.NET architecture.
This position is ideal for engineers who enjoy solving challenging technical problems, taking ownership of features from concept to production, and troubleshooting complex issues in real-world environments.
What You'll Do
- Design, develop, test, and maintain backend services and applications using C# and .NET.
- Take ownership of complex features throughout the full software development lifecycle.
- Collaborate with product managers, engineers, and other stakeholders to deliver high-quality solutions.
- Participate in technical design discussions and evaluate architectural trade-offs.
- Investigate and resolve production issues using logs, telemetry, diagnostics, and root-cause analysis techniques.
- Improve system reliability, performance, maintainability, and supportability.
- Contribute to code reviews and engineering best practices.
- Support modernization initiatives, including migration of selected legacy components to C#/.NET.
- Help drive high standards for quality, testing, and software craftsmanship.
Required Qualifications
- Strong professional experience developing backend applications with C# and .NET.
- Proven experience owning and delivering complex software features from design through release.
- Experience working on large-scale commercial products rather than only isolated services or short-term projects.
- Strong debugging and troubleshooting skills.
- Solid understanding of software engineering principles, including:
- Concurrency and multithreading
- Networking fundamentals
- Testing strategies
- Reliability and maintainability
- Performance optimization
- Ability to work independently while collaborating effectively within a team.
- Strong problem-solving and communication skills.
Preferred Qualifications
- Experience modernizing legacy systems or migrating applications to newer technologies.
- Exposure to customer-hosted, on-premises, infrastructure, storage, backup, endpoint, or systems-management products.
- Experience integrating with cloud platforms such as AWS or Microsoft Azure.
- Knowledge of distributed systems, infrastructure software, or storage technologies.
Working Environment
- Hybrid working model based in Warsaw.
- Collaborative engineering culture focused on ownership, quality, and continuous improvement.
- Opportunity to contribute to a mature product while shaping its future evolution.
- Exposure to challenging technical problems and real-world production environments.
What Success Looks Like
In this role, you will:
- Deliver high-quality features that provide measurable customer value.
- Demonstrate strong technical judgment and ownership.
- Improve product reliability, performance, and maintainability.
- Effectively diagnose and resolve complex production issues.
- Contribute to engineering excellence through collaboration, reviews, and knowledge sharing.
- Support modernization efforts that help evolve the platform for future growth.
What you need to do now
If you're interested in this role, click 'apply now' to forward an up-to-date copy of your CV, or call us now.
Hays Poland sp. z o.o. is an employment agency registered in a registry kept by Marshal of the Mazowieckie Voivodeship under the number 361.
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