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

Sii Poland; Kraków; Hybrid; PLN 180,000 - 300,000; Full time

Benefits offered by this job

Great Place to Work

Profit sharing

Medical care

Centre of internal trainings

MySii app

Regular integration events and trips

Comfortable offices

Job summary

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

The role involves Terraform IaC, Azure DevOps pipelines, security best practices, and observability efforts.

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.
• Practical knowledge of building and securing REST APIs with validation and authentication.
• Experience with automated testing frameworks like xUnit and Jest / Vitest.
• 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.
• Familiarity with observability tools like 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#

ASP.NET Core

React

TypeScript

Azure

EF Core

Azure DevOps

REST APIs

xUnit

Jest

Tools

Terraform

Azure DevOps

xUnit

Jest

Vitest

Azure Functions

Application Insights

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 disciplineAdvanced level of English

Nice to have

• Knowledge of observability practices
• Experience with automated testing

Job no. JOB-7CTY4

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