Job Description

About the role
We 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).
Responsibilities
- Develop 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 skills
- Commercial 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 requirements - Polish native or C2 level (required) - English professional level enabling work with technical documentation
Nice to have
- Experience 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