Senior .NET Developer

Senior .NET Developer Miejsce pracy: Warszawa Technologies we use Expected • .NET • C# • SoapUI • SQL About the project Start: December 1, 2026 Location: hybrid work in Warsaw (3 days per week working from Warsaw office) This is how we organize our work This is how we work • at the client's site Your responsibilities • Maintain and extend the Windows Service (C#, .NET Framework), including its multi-threaded, timer-driven import and export processing. • Develop and optimise SQL Server data access: stored procedures, Dapper-based repositories, and handling of deadlocks, locking and performance issues. • Maintain mappings between canonical data models for shipments, status events, milestones and customs declarations, using AutoMapper and custom merge logic. • Maintain and update WCF/SOAP integrations, such as the DAAC master data and configuration services and the export service agents. • Provide 2nd/3rd-level production support: analyse data issues, reprocess or correct records, and resolve incidents together with operations and business teams. • Document the current solution and contribute to its modernisation roadmap, e.g. migrating to modern .NET, standard dependency injection and REST-based integrations. • Drive quality through unit and integration testing Our requirements • You are an experienced, quality-focused developer who is comfortable working with established enterprise systems, enjoys solving complex data problems, and communicates clearly with both technical and business stakeholders. • 5+ years of proven experience as a .NET Developer, Software Engineer, or in a similar role. • Strong proficiency in C# and .NET Framework 4.x, including Windows Services, multithreading with the Task Parallel Library. • Solid experience with Microsoft SQL Server and T-SQL: backup, stored procedures, query tuning, transactions, isolation levels and deadlock analysis. • Hands-on experience with WCF/SOAP services, including generating and maintaining service references and configuring bindings and endpoints. • Experience with XML serialization and XSD schemas, XLST maps, and with object mapping libraries such as AutoMapper • Familiarity with dependency injection (e.g. Unity) What we offer We offer a full-time employment contract • Location – Warsaw; work model – hybrid • Stable and long-term cooperation • Well-defined career path at the European leader in engineering & IT consulting • Opportunity to relocate and work in different ALTEN Polska branches • After completion of the project, opportunity to engage in a subsequent one within the company • Introduction and cooperation with dedicated Competences Manager We also offer cooperation based on a B2B or Contract of mandate (UZ). We also guarantee: • Access to professional certifications with our technology partners (e.g. Google, ISTQB) • Access to relevant industry events • Access to the Knowledge Sharing Program • Access to Referral program Benefits • life insurance • retirement pension plan • baby layette • employee referral program • Medicover medical care • Medicover dental care • Medicover Benefits platform • Medicover Sport card ALTEN Polska WHO ARE WE? WE ARE A WORLD LEADER IN ENGINEERING AND IT SERVICES. At ALTEN, we see our specialists as architects – today’s designers of tomorrow’s world. As a leader in Engineering and IT Services, we support companies in their technological and sustainable transformation. OVER 57,400 EMPLOYEES IN 30+ COUNTRIES, TO SUPPORT MORE THAN 6,500 CLIENTS WORLDWIDE. We operate in all sectors: Aeronautics, Space, Defence, Security & Naval, Automotive, Rail & Mobility, Energy & Environment, Life Sciences & Health, Industrial Equipment & Electronics, Telecoms, Banking, Finance & Insurance, Retail, Services & Medias, Public Services & Government. We carry out complex and highly technical projects throughout the value chain of the most prestigious companies worldwide. Our motto: Building Tomorrow’s World Today! Wszystkie informacje o przetwarzaniu danych osobowych w tej rekrutacji znajdziesz w formularzu aplikacyjnym, po kliknięciu w przycisk "Aplikuj Teraz".