.Net Developer

Billennium; Polska; Hybrid; PLN 180,000 - 280,000; Full time

Benefits offered by this job

Udemy for Business

Private medical care

Multisport card

Veterinary package

Language lessons

Shopping vouchers

Hybrid/remote work options

Welcome pack

Job summary

Billennium is a global technology company delivering advanced digital solutions. We seek a .NET Developer to join our team and support backend development for a life sciences client. You will build secure platforms, create Web APIs and GraphQL services, and contribute to clean code and robust testing in an Agile setting.

You will work on backend applications, implement features, and collaborate with engineers to deliver high-quality software for regulated environments.

Qualifications

• 3+ years of commercial .NET development experience.
• Strong knowledge of C#, .NET Core/7, and ASP.NET Core.
• Experience building backend REST APIs and GraphQL.
• Familiar with SQL Server and testing frameworks MSTest/NSubstitute.

Responsibilities

• Develop and maintain backend applications using .NET technologies.
• Implement new features and improve existing functionalities following Domain-Driven Design (DDD) principles.
• Build and maintain Web APIs and GraphQL-based services.
• Create and maintain unit and integration tests.
• Support application upgrades and modernization initiatives.
• Analyze and estimate development tasks.
• Participate in code reviews and contribute to improving code quality.
• Collaborate with developers, testers, and business stakeholders in an Agile environment.
• Troubleshoot issues and optimize application performance.

Skills

C#

.NET Core/.NET 7

ASP.NET Core

REST APIs

GraphQL

SQL Server

Unit & Integration Testing

Git

AWS S3

DDD

Tools

MSTest

NSubstitute

CI/CD

Job description

Billennium is a global technology company with over 20 years of experience, committed to innovation and empowering businesses. As an employer, we offer a supportive, growth-focused environment where collaboration and creativity thrive. Join us to shape the future of technology together!

We are looking for a .NET Developer to join our team and support the development of advanced digital solutions for a global client from the life sciences industry.

In this role, you will contribute to the development of a secure platform supporting scientific and diagnostic processes. You will work on backend applications responsible for managing and processing business-critical data in a regulated environment, collaborating with experienced engineers and contributing to high-quality software solutions.

What you will do

• Develop and maintain backend applications using .NET technologies
• Implement new features and improve existing functionalities following Domain-Driven Design (DDD) principles
• Build and maintain Web APIs and GraphQL-based services
• Create and maintain unit and integration tests
• Support application upgrades and modernization initiatives
• Analyze and estimate development tasks
• Participate in code reviews and contribute to improving code quality
• Collaborate with developers, testers, and business stakeholders in an Agile environment
• Troubleshoot issues and optimize application performance

What we are looking for

• 3+ years of commercial experience in .NET development
• Strong knowledge of C#, .NET Core/.NET 7, and ASP.NET Core
• Experience developing backend applications and REST APIs
• Knowledge of GraphQL, including working with queries and mutations
• Experience with SQL Server and relational databases
• Practical experience with unit and integration testing
• Familiarity with MSTest, NSubstitute, or similar testing frameworks
• Understanding of Dependency Injection and ASP.NET Core fundamentals
• Basic knowledge of Authentication and Authorization mechanisms
• Experience working with Git
• Familiarity with AWS services, ideally Amazon S3
• Experience working in Agile teams
• Good analytical and problem-solving skills
• Good communication skills and proactive attitude

Nice to have

• Experience with Domain-Driven Design (DDD)
• Experience with GraphQL subscriptions
• Experience in healthcare, life sciences, pharmaceutical, or other regulated industries
• Familiarity with CI/CD practices

Perks and benefits (our offer)

• Comprehensive benefits – enjoy Udemy for Business, private medical care, Multisport card, veterinary package, language lessons, and shopping vouchers
• Flexibility – adaptable working hours and remote/hybrid work options
• Career growth – development opportunities and access to training within partnerships with Microsoft, AWS, Snowflake, Salesforce & more
• Global collaboration – work with an international team
• Innovative environment – contribute to impactful solutions supporting the life sciences industry
• Engaging community – team-building events, CSR initiatives, and hackathons
• Welcome pack to kick off your journey with us

Tech Stack: C#, .NET 7, .NET Core, ASP.NET Core, Web API, GraphQL, SQL Server, MSTest, NSubstitute, Domain-Driven Design (DDD), Integration Testing, Dependency Injection, Authentication & Authorization, Amazon S3, Git, Agile.