Senior .NET Developer (Banking) – Remote (Poland)

Work model: 100% remote (candidates must be based in Poland) Contract type: B2B Industry: Banking / Investment Banking We are looking for an experienced Senior .NET Developer to join a distributed engineering team working on critical banking systems. The role focuses on extending and modernising applications used across securities and banking operations, with a strong emphasis on system design, scalability, and cloud transformation. You will work end-to-end on business-critical systems, closely collaborating with Business Analysts, without a separate QA team. A solid background in banking or financial services is essential. Main Responsibilities:• Design, develop, and extend .NET-based systems supporting multiple banking entities • Contribute to the integration of securities and core banking platforms • Support and enhance a portfolio of ~17 applications across product control and risk management • Work with an in-house development framework in a full-stack capacity • Participate in scaling applications for cloud-based, containerized environments • Collaborate closely with business stakeholders to deliver robust solutions • Ensure high code quality through unit and integration testing Key Requirements:• 5+ years of professional experience as a .NET / C# Developer • Hands-on experience in the banking or investment banking sector (mandatory) • Full-stack development experience (backend-focused, frontend included) • Strong understanding and practical application of SOLID design principles • Experience with document-based databases (e.g. MongoDB) • Experience with event-driven / event-based messaging frameworks • Solid knowledge of unit and integration testing • Experience working end-to-end on applications (development, testing, support) • Ability to work independently in a fast-paced, regulated environment • Availability during UK business hours Nice to Have:• Experience with cloud platforms and application migration to cloud • Experience with container technologies (e.g. Docker, Kubernetes) • Exposure to systems such as Murex or large in-house banking platforms • Background in securities, risk, or product control systems Other Details:This role is 100% remote with candidates required to be located in Poland. The contract is on a B2B basis within the banking and investment banking industry.