Senior Software .NET Engineer

Reply; Katowice; Hybrid; PLN 179,000 - 246,000; Full time

Benefits offered by this job

Motivizer Benefits Platform (PLN 550/月

Language Courses

Internal community & events

Regular training opportunities

Job summary

Nexi Digital is seeking a Senior Software Engineer to drive the modernization of a payment platform by migrating a large ASP.NET WebForms/MVC monolith from .NET Framework 4.x to .NET 8, including database and system integrations in an on-premise setup.

You will leverage AI-assisted development tools, refactor for SOLID and clean architecture, and build automated tests to verify migration steps, while mentoring teammates and collaborating with stakeholders.

Qualifications

• University degree in computer science or a comparable field of study.
• 6+ years of commercial software development experience.
• Experience with C# and .NET across generations (ASP.NET WebForms/MVC and ASP.NET Core).
• Experience migrating legacy applications (re-platforming, incremental refactoring).
• Strong knowledge of SOLID and clean architecture.
• Experience with SQL Server and data-layer refactoring.
• Experience with AI-assisted development tools on daily workflow.
• Fluency in Polish and very good English communication.
• Hybrid work availability; monthly office visits.

Responsibilities

• Analyze legacy codebase and plan incremental migration paths.
• Migrate components from .NET Framework to .NET 8 / ASP.NET Core.
• Refactor towards SOLID and clean architecture during migration.
• Modernize SQL Server data layer and integrations.
• Leverage AI tools to accelerate analysis, refactoring, and testing.
• Build automated unit and integration tests for migration verification.
• Collaborate with teams and stakeholders on scope and sequencing.
• Mentor junior developers and share modernization know-how.

Skills

C#

.NET

ASP.NET WebForms

SQL Server

AI-assisted development

Unit testing

Polish

English

Education

CS degree or equivalent

Tools

GitHub Copilot

LLM tools

Job description

Responsibilities

As a Senior Software Engineer at Nexi Digital, you will drive the modernization of an established, business-critical payment platform - migrating a large ASP.NET (WebForms/MVC) monolith from .NET Framework 4.x to .NET 8, together with its database layer and system integrations, in an on-premise environment. You will combine deep .NET craftsmanship with modern, AI-assisted ways of working to make the migration faster and safer.

• Analyzing the legacy codebase and shaping an incremental, low-risk migration path (module by module, no big-bang rewrites)
• Designing and implementing the migration of application components from .NET Framework 4.x / ASP.NET (WebForms, MVC) to .NET 8 / ASP.NET Core
• Refactoring the code towards SOLID principles and clean architecture as part of the migration, not as a separate project
• Modernizing the Microsoft SQL Server data layer and the platform's integrations with surrounding systems
• Using AI-assisted development tools (e.g. GitHub Copilot and LLM-based tooling) to accelerate legacy code analysis, refactoring and test generation - and helping the team adopt these practices responsibly
• Building the automated test coverage (unit, integration) that makes the migration verifiable at every step
• Collaborating closely with the development teams and stakeholders on scope, sequencing and technical decisions
• Mentoring less experienced developers and sharing modernization know-how across the team

Benefits

• Motivizer Benefits Platform to choose and manage all your benefits in one place. You receive a budget (550 PLN monthly). You can choose medical care package, meal tickets, sports cards (we have Multisport and on preferential terms, we have membership cards to one of the most popular Gyms), cinema tickets, shop vouchers, discounts and many more.
• Language Courses - you'll have access to a multi-language learning platform enabling you to practice you language skills and learn new ones!
• Regular and systematic further training opportunities - both internally and from external providers. We support your ongoing learning and development.
• Cooperation within an internal community is our everyday reality. We have networking events, coding challenges, and company parties for different occasions.

Qualifications

• Successfully completed university degree in computer science or a comparable field of study
• 6+ years of commercial software development experience
• Extensive experience with C# and .NET across generations - both .NET Framework 4.x (ASP.NET WebForms/MVC) and modern .NET (6/8) with ASP.NET Core
• Hands-on experience with modernizing or migrating legacy applications (re-platforming, incremental refactoring, strangler-fig-style approaches)
• Strong knowledge of software design principles and patterns, including SOLID and clean architecture
• Solid experience with Microsoft SQL Server and data-layer refactoring
• Practical experience with AI-assisted development (e.g. GitHub Copilot or similar LLM-based tools) as part of your daily engineering workflow
• Experience with automated unit and integration testing
• Fluency in Polish and very good communication in English
• Availability to work in a hybrid mode. Remote workers, we invite to the office once every month

Salary range

Employment Contract: 16 000 - 22 000 PLN gross/month

B2B Contract: 160 - 180 PLN net/h (Benefits not applicable on B2B cooperation type)

About Nexi Digital

Nexi is Europe's PayTech company operating in high-growth, attractive European markets and technologically advanced countries. Listed on Borsa Italiana's MTA, Nexi has the scale, geographic reach and abilities to drive the transition to a cashless Europe. With its portfolio of innovative products, e-commerce expertise and industry-specific solutions, Nexi provides flexible support for the digital economy and the entire payment ecosystem globally, across a broad range of different payment channels and methods. Nexi’s technological platform and the best-in-class professional skills in the sector lets the company operate at its best in three market segments: Merchant Services & Solutions, Cards & Digital Payments and Digital Banking & Corporate Solutions. Nexi constantly invests in technology and innovation, focusing on two fundamental principles: meeting, together with its partner banks, customer needs and creating new business opportunities for them. Nexi is committed to supporting people and businesses of all sizes, transforming the way people pay and businesses accept payments. It offers companies the most innovative and reliable solutions to better serve their customers and expand. By simplifying payments and enabling people and businesses to build closer relationships and grow together, Nexi promotes progress to benefit everyone.