Senior .NET Developer with Azure - banking industry (f/m/x)

Sii Poland; Kraków; Hybrid; PLN 180,000 - 230,000; Full time

Benefits offered by this job

Great Place to Work

Solid financial situation

Contracts with the biggest brands

Centre of internal trainings

Many experts you can learn from

Open and accessible management team

Profit sharing

Passion Sponsorship program

Regular integration events and trips

Comfortable and well-equipped offices

MySii app

Medical care

Job summary

Sii Poland in Kraków is seeking a versatile Senior .NET Developer to join our modernization program, migrating legacy applications to cloud-native Azure. You will work across backend, frontend, database, and cloud/DevOps, developing .NET APIs, React microfrontends, and Azure services.

The role is based in Cracow with a hybrid work model. You will design backend services, build React microfrontends, manage MSSQL/Azure SQL, Terraform IaC, and CI/CD pipelines in Azure DevOps, while ensuring

Qualifications

• Minimum 5 years of commercial full-stack experience with C#/.NET (including .NET 6+/9) and ASP.NET Core.
• Strong skills in EF Core and MSSQL / Azure SQL, including query tuning and stored procedures.
• Hands-on experience with Azure services such as App Service, Azure SQL, and Functions.
• Proficiency in Infrastructure as Code using Terraform for multi-environment provisioning.
• Experience with CI/CD processes in Azure DevOps, including YAML pipelines-as-code.
• Practical knowledge of building and securing REST APIs with validation and authentication.
• Experience with automated testing frameworks like xUnit and Jest / Vitest.
• Familiarity with observability tools such as Application Insights and structured logging.
• Good Git practices and code review discipline.
• Advanced level of English

Responsibilities

• Designing and implementing backend services and REST APIs in .NET 9 using Clean Architecture.
• Building and maintaining React + TypeScript microfrontends.
• Evolving MSSQL / Azure SQL schemas.
• Authoring and maintaining Infrastructure as Code in Terraform for Azure resource management.
• Building, optimizing, and supporting CI/CD pipelines in Azure DevOps.
• Integrating Azure AD authentication and applying security best practices.
• Instrumenting services for observability and health checks.
• Reading, refactoring, and extracting business logic from legacy .NET and T-SQL during migration.
• Writing and maintaining automated tests including unit, integration, and E2E tests.
• Troubleshooting production incidents and supporting deployments.

Skills

C# / .NET

ASP.NET Core

EF Core

Azure

Terraform

Azure DevOps

REST APIs

TypeScript

React

Git

Tools

Terraform

Azure DevOps

SQL Server / MSSQL

CI/CD pipelines

Job description

We are looking for a versatile Senior .NET Developer to join the modernization program, migrating a portfolio of legacy applications to a cloud-native Azure architecture. In this role, you will work on a variety of tasks across backend, frontend, database, and cloud/DevOps, contributing to the development of .NET APIs, React microfrontends, and Azure services. This position is based in Cracow and offers a hybrid work model. If you are passionate about modernizing applications and enjoy working in a collaborative environment, this opportunity may be the right fit for you.

Your tasks

• Designing and implementing backend services and REST APIs in .NET 9 using Clean Architecture
• Building and maintaining React + TypeScript microfrontends
• Evolving MSSQL / Azure SQL schemas
• Authoring and maintaining Infrastructure as Code in Terraform for Azure resource management
• Building, optimizing, and supporting CI/CD pipelines in Azure DevOps
• Integrating Azure AD authentication and applying security best practices
• Instrumenting services for observability and health checks
• Reading, refactoring, and extracting business logic from legacy .NET and T-SQL during migration
• Writing and maintaining automated tests including unit, integration, and E2E tests
• Troubleshooting production incidents and supporting deployments

Requirements

• Minimum 5 years of commercial full-stack experience with C# /.NET (including .NET 6+/9) and ASP.NET Core
• Strong skills in EF Core and MSSQL / Azure SQL, including query tuning and stored procedures
• Hands-on experience with Azure services such as App Service, Azure SQL, and Functions
• Proficiency in Infrastructure as Code using Terraform for multi-environment provisioning
• Experience with CI/CD processes in Azure DevOps, including YAML pipelines-as-code
• Practical knowledge of building and securing REST APIs with validation and authentication
• Experience with automated testing frameworks like xUnit and Jest / Vitest
• Familiarity with observability tools such as Application Insights and structured logging
• Good Git practices and code review discipline
• Advanced level of English

Nice to have

• Knowledge of observability practices
• Experience with automated testing

Job no. JOB-XBDZZ

Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.

Benefits For You

• Great Place to Work
• Solid financial situation
• Contracts with the biggest brands
• Centre of internal trainings
• Many experts you can learn from
• Open and accessible management team
• Profit sharing
• Passion Sponsorship program
• Regular integration events and trips
• Comfortable and well-equipped offices
• MySii app
• Medical care