Workplace type: Remote-first (with on-site team meetings twice a month in Warsaw)Contract type: B2B / Permanent (UoP)Salary (B2B): 120 – 135 PLN + VAT / hourAvailability: ASAP/ up to 1 monthWe are currently looking for a Senior .NET Developer to join a long-term enterprise banking project. You will work on scalable backend and fullstack applications delivered in a modern development environment with strong focus on code quality, automation and stable delivery processes. This role is ideal for an experienced engineer who takes ownership of delivered solutions, actively participates in technical decisions and supports high engineering standards across the team.Responsibilities Design and develop backend services using C# and .NET Core / .NET Framework Build and extend frontend components using Angular and JavaScript Design and maintain REST APIs Develop scalable enterprise applications Create and maintain automated tests (unit and E2E – Cucumber) Participate in technical and architectural discussions Take ownership of code quality and code review standards Work with CI/CD pipelines and deployment automation Collaborate with DevOps, QA, Analysts and Product teams Support less experienced developers through technical guidance Must have (Senior level) Strong commercial experience with C#, .NET Core and .NET Framework Advanced knowledge of Angular and JavaScript Deep understanding of SOLID principles, design patterns, IoC and DI Advanced experience with unit testing and automated E2E testing (Cucumber) Strong REST API development skills Experience working on large-scale enterprise systems Advanced experience with Docker and Kubernetes Knowledge of CI/CD processes Experience with Jira, Git, TeamCity or Jenkins Native or near-native (C2) proficiency in Polish Nice to have Experience with cloud platforms (Azure, GCP) Ansible or GitHub Actions PowerShell Enterprise integration experience Microsoft certifications (.NET / ASP.NET) Margo Offers: Long-term cooperation on stable banking project Remote-first work model with regular on-site collaboration days Employment or B2B contract (based on your preference) Benefits such as medical care and sports card Opportunity to grow in enterprise-scale systems Collaboration with experienced developers and architects Friendly and supportive MARGO team