Regular .NET Developer (Card Payment Systems)

About the roleWe are looking for a Regular .NET Developer to join a team responsible for developing and maintaining core card payment systems - from transaction authorization and settlement to integrations with external payment services.The systems process hundreds of thousands of transactions daily, so performance, availability and security are key priorities.Work model: Remote-first with scheduled on-site team meetings (2 days per month in Warsaw).ResponsibilitiesDevelop and maintain .NET applications in card payment domain Design and implement new functionalities according to business and regulatory requirements Integrate systems with external services (REST, SOAP, messaging queues) Optimize performance, availability and security of applications Cooperate with Analysts, Architects and QA in Agile/Scrum teams Participate in SIT/UAT testing, code reviews and preparation of technical documentation Required skillsCommercial experience with C# and .NET (Framework / Core) Experience with ASP.NET Core, Angular and WebAPI Knowledge of Entity Framework, LINQ, Dapper Experience with SQL Server (T-SQL) and query optimization Knowledge of SOLID principles and design patterns Experience writing unit tests (xUnit / NUnit) Experience with system integrations (REST, SOAP, JSON, XML) Experience working in Agile environment Knowledge of Git, CI/CD and TeamCity Language requirementsPolish: native or C2 level (required) English: professional level enabling work with technical documentation Nice to haveExperience in card payments / payment processing domain Knowledge of Docker / Kubernetes Experience working on high-availability or complex distributed systems Margo Offers:B2B cooperation Remote working model Benefits such as medical care and sports card Co-financing trainings, certification exams and post-graduate studies Ability to work in an international consulting company on ambitious projects Possibility to get involved in outside-project activities with additional remuneration) Excellent working atmosphere, integration events Originally posted on Himalayas