Regular .NET Developer

Workplace type: Remote-first (with on-site team meetings twice a month in Warsaw)Contract type: B2B / Permanent (UoP)Salary (B2B): 100 – 110 PLN + VAT / hour

Availability: ASAP/ up to 1 month

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:

• 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