Senior Full Stack .NET Developer

Synechron; Kraków; On-site; PLN 230,000 - 290,000; Full time

Job summary

Synechron in Kraków is seeking an experienced software engineer to design, develop, and support scalable enterprise solutions built with .NET, React, and SQL Server. You will contribute to robust backend services, modern UI components, and efficient data access patterns in a fast-paced environment.

You’ll work across the full SDLC, mentor teammates, and help drive CI/CD automation while collaborating with product teams and DevOps professionals to deliver high-quality software that improves

Qualifications

• 7+ years of professional experience developing and supporting production applications in the .NET ecosystem.
• Strong proficiency in C#, ASP.NET Core/Web API, and backend development.
• Hands-on experience with React and modern front-end development.
• Advanced knowledge of SQL Server, T-SQL, database design, query optimization, and performance tuning.
• Proven experience with CI/CD.
• Strong understanding of the Software Development Life Cycle (SDLC).
• Excellent troubleshooting, problem-solving, communication, and stakeholder-management skills.

Responsibilities

• Design and implement robust solutions using industry-standard design patterns.
• Analyze business requirements and recommend effective technical improvements.
• Develop scalable and secure backend services using C# and Web API.
• Build dynamic, responsive, and high-performance user interfaces using React.
• Lead UI enhancements to improve user experience, application stability, and performance.
• Design and optimize databases, queries, and stored procedures using SQL Server and T-SQL.
• Contribute to software architecture, technical design, and application prototypes.
• Drive CI/CD automation and continuously improve the DevOps lifecycle.
• Participate across the complete SDLC—from requirements gathering through deployment and maintenance.
• Manage changes through the service management lifecycle.
• Troubleshoot and resolve complex production issues in a high-pressure environment.
• Work closely with customers to understand their needs and deliver timely, effective solutions.

Skills

C#

ASP.NET Core/Web API

React

SQL Server

CI/CD

SDLC

Troubleshooting

Communication

Job description

Synechron is a global technology consulting firm that helps leading organizations accelerate digital transformation through innovation, expertise, and agility. With more than 16,500 professionals across around 60 offices in over 20 countries, we combine deep industry knowledge with advanced capabilities in AI, cloud, cybersecurity, and data engineering. Our regional teams, supported by strategic delivery centers, provide scalable, cost-efficient solutions tailored to local markets. Through our award-winning Synechron FinLabs accelerators and strategic partnerships with AWS, Microsoft, Databricks, Salesforce, and ServiceNow, we enable clients to innovate fast and lead with confidence. For more information on the company, please visit our website or LinkedIn community.

Diversity, Equity, and Inclusion:

Diversity & Inclusion are fundamental to our culture, and Synechron is proud to be an equal opportunity workplace and an affirmative-action employer. Our Diversity, Equity, and Inclusion (DEI) initiative ‘Same Difference’ is committed to fostering an inclusive culture – promoting equality, diversity and an environment that is respectful to all. We strongly believe that a diverse workforce helps build stronger, successful businesses as a global company. We encourage applicants from across diverse backgrounds, race, ethnicities, religion, age, marital status, gender, sexual orientations, or disabilities to apply. We empower our global workforce by offering flexible workplace arrangements, mentoring, internal mobility, learning and development programs, and more.

All employment decisions at Synechron are based on business needs, job requirements and individual qualifications, without regard to the applicant’s gender, gender identity, sexual orientation, race, ethnicity, disabled or veteran status, or any other characteristic protected by law.

Job Description:

Are you a hands-on software engineer passionate about building scalable applications, improving user experiences, and driving DevOps excellence? Join our team and play a key role in designing, developing, and supporting high-quality enterprise solutions.

What You’ll Do:

• Design and implement robust solutions using industry-standard design patterns.
• Analyze business requirements and recommend effective technical improvements.
• Develop scalable and secure backend services using C# and Web API.
• Build dynamic, responsive, and high-performance user interfaces using React.
• Lead UI enhancements to improve user experience, application stability, and performance.
• Design and optimize databases, queries, and stored procedures using SQL Server and T-SQL.
• Contribute to software architecture, technical design, and application prototypes.
• Drive CI/CD automation and continuously improve the DevOps lifecycle.
• Participate across the complete SDLC—from requirements gathering through deployment and maintenance.
• Manage changes through the service management lifecycle.
• Troubleshoot and resolve complex production issues in a high-pressure environment.
• Work closely with customers to understand their needs and deliver timely, effective solutions.

What We’re Looking For:

• 7+ years of professional experience developing and supporting production applications in the .NET ecosystem.
• Strong proficiency in C#, ASP.NET Core/Web API, and backend development.
• Hands-on experience with React and modern front-end development.
• Advanced knowledge of SQL Server, T-SQL, database design, query optimization, and performance tuning.
• Proven experience with Continuous Integration and Continuous Delivery (CI/CD).
• Strong understanding of the Software Development Life Cycle (SDLC).
• Excellent troubleshooting, problem-solving, communication, and stakeholder-management skills.
• Ability to work effectively in a fast-paced environment while maintaining a strong focus on quality and stability.
• Work on impactful, enterprise-grade applications.
• Contribute to architecture, innovation, and continuous improvement.
• Collaborate with talented engineering, DevOps, and product teams.
• Make a measurable impact on customer experience and application performance.