Senior Full Stack .NET Developer

Job Opportunity: Senior Fullstack .NET Developer (React) Location: Kraków, hybrid model (6 office days per month) Type of contract: B2B English: B2+ Role Overview We are looking for a Senior Fullstack .NET Developer to join a team that builds and maintains web applications used by a broad group of business users. The role covers the full application stack, from the database and backend services to the user interface, together with the automation that takes code to production. This is a technical, delivery-focused position for someone who implements changes themselves, takes part in shaping the architecture and stays close to the users of the applications. You will work in a mature environment with a structured approach to change management and production stability. Responsibilities: Build new features and backend services in C# and .NET, applying proven design patternsDrive front-end improvements in React that raise usability and application stabilityReview incoming requirements, clarify the intended solution and propose better approachesContribute to architecture decisions for new and existing componentsBuild prototypes to validate ideas and designs before full implementationAutomate build and deployment processes and keep improving the CI/CD pipelinesTake changes through a formal change management process up to production releaseSupport application users: diagnose and fix reported issues quickly and work with them to find the right solution Requirements: 7+ years of commercial experience building production applications in the .NET ecosystemStrong C# skills and experience designing Web APIs and secure, scalable backend servicesSolid experience building complex, high-performing web applications in ReactGood command of SQL Server: database design, T-SQL, query optimization and performance tuningPractical experience with CI/CD and wider DevOps practicesAbility to troubleshoot, resolve and prevent production issues under time pressureExperience across the full software development lifecycle, from requirements to maintenanceStrong analytical skills and attention to the quality of delivered work What we offer: B2B contract.Private medical care, life insurance, and access to Multisport card.Stable, long-term projects with full-time employment. If you're an experienced .NET or Fullstack Developer with a passion for building reliable, well-designed web applications and enjoy owning features from the database to the UI – I'd be glad to hear from you!