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

Sii Poland; Kraków; Hybrid; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Great Place to Work

Centre of internal trainings

Profit sharing

Medical care

Open management team

Trips and integration events

MySii app

Flexible work hours

Job summary

Sii Poland is seeking a versatile Senior .NET Developer to join a modernization program in Kraków. You will migrate legacy applications to a cloud-native Azure architecture, building .NET APIs, React microfrontends, and Azure services in a hybrid work setting.

Responsibilities include backend and frontend development, database tuning, IaC with Terraform, CI/CD in Azure DevOps, and implementing secure authentication with Azure AD. Strong English communications are required.

Qualifications

• Minimum 5 years of commercial full-stack .NET experience (C#, ASP.NET Core).
• Strong EF Core and MSSQL/Azure SQL with query tuning skills.
• Hands-on Azure (App Service, SQL, Functions) and Terraform IaC.
• Experience with Azure DevOps YAML pipelines and CI/CD workflows.
• Proficient in building secure REST APIs and modern frontend with React/TypeScript.
• Experience in automated tests (xUnit/Jest) and observability tools.

Responsibilities

• Design and implement backend services and REST APIs in .NET 9 using Clean Architecture.
• Develop React + TypeScript microfrontends and integrate with APIs.
• Evolve MSSQL / Azure SQL schemas and performance tuning.
• Author/maintain Terraform IaC for Azure resources.
• Build and optimize CI/CD pipelines in Azure DevOps.
• Implement Azure AD auth and security best practices.
• Instrument services for observability and health checks.
• Refactor legacy .NET/T-SQL during migration.
• Write/maintain automated tests (unit, integration, E2E).
• Troubleshoot production incidents and support deployments.

Skills

C# / .NET

ASP.NET Core

EF Core

Azure

React

TypeScript

MSSQL / Azure SQL

Terraform

Azure DevOps

REST APIs

CI/CD pipelines

xUnit / Jest

Observability

Git

Tools

Azure DevOps

Terraform

Jest

Kubernetes

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

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

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.