C#/.NET Senior Backend Developer

We are **tech transformation** specialists, uniting human expertise with AI to create scalable tech solutions. With over 8,000 CI\&Ters around the world, we’ve built partnerships with more than 1,000 clients during our 30 years of history. Artificial Intelligence is our reality. **Your Goal:** Deliver scalable system enhancements that expand business capabilities, enable multi\-brand operations, and ensure sustainable platform evolution.Design and evolve application architecture to support flexible data models, modular integrations, and growing operational demands.Improve reliability, performance, and maintainability of existing solutions while enabling future integrations and parallel initiatives.Promote structured knowledge transfer to strengthen internal ownership and foster long\-term autonomy in development. **Key Responsibilities:** Design, build, and maintain backend services and system integrations. Develop and maintain web and desktop applications supporting business operations. Implement and evolve integrations through APIs, service\-based communication, and file\-based data exchanges. Develop and maintain background processing services with scheduled jobs. Work with relational databases, including schema design, query optimisation, and performance tuning. Apply structured data access patterns to ensure maintainability and consistency.Integrate systems through messaging and file transfer mechanisms. Apply security best practices for authentication, authorisation, and secure application development. Contribute to CI/CD pipelines and support containerization initiatives for application deployment and environment consistency. Troubleshoot production issues through log analysis, debugging, and root\-cause investigation. Collaborate with cross\-functional teams, ensuring clear communication and ownership of deliverables. Participate in technical discussions, design reviews, and support knowledge sharing across the team. **Required Skills and Qualifications:** Strong experience with **C\# and .NET Framework 4\.8 in production environments. Hands\-on experience with **ASP.NET **Web API 5\.3 and **ASP.NET **MVC 5\.2 . Solid understanding of **RESTful services , **SOAP/WCF , and system integration patterns. Experience building **Windows desktop applications using **WinForms and/or **WPF . Proficiency with **SQL Server and **Entity Framework (EF 6\.2 / EF Core 2\.2\) . Experience implementing the **Repository Pattern for structured data access. Practical knowledge of **Windows Services and job scheduling with **Quartz . Familiarity with **file\-based integrations (XML, CSV), **message queues , and **FTP workflows . Basic understanding of **CI/CD practices and application **containerization concepts . Ability to troubleshoot legacy and distributed systems, analyse logs, and resolve performance issues. Effective communication and ability to work in collaborative team environments. Advanced English. **Soft Skills:** Proactive ownership of tasks and commitment to continuous improvement. Strong communication skills with both technical and non\-technical stakeholders. Ability to balance multiple priorities in evolving environments. Collaborative team player who values shared outcomes and knowledge exchange. Adaptable mindset when working with legacy systems and changing requirements. **Nice\-to\-have Skills:** Experience working across both modern and legacy .NET applications within the same ecosystem. Familiarity with maintaining long\-running enterprise background services. Comfort working with mixed integration patterns (API, file transfer, messaging). Experience participating in modernisation or migration initiatives within .NET environments. Hands\-on experience with **OAuth 2\.0 , **IdentityServer3 , **ASP.NET **Identity , and **Azure AD . **Our benefits:** \-Health and dental insurance \-Meal and food allowance \-Childcare assistance \-Extended paternity leave \-Partnership with gyms and health and wellness professionals via Wellhub (Gympass) TotalPass; \- Profit Sharing and Results Participation (PLR); \-Life insurance \- Continuous learning platform (CI\&T University); \-Discount club \-Free online platform dedicated to physical, mental, and overall well\-being \-Pregnancy and responsible parenting course \-Partnerships with online learning platforms \-Language learning platform And many more! More details about our benefits here: https://ciandt.com/br/pt\-br/carreiras At CI\&T, inclusion starts at the first contact. If you are a person with a disability, it is important **to present your assessment during the selection process. *See which data needs to be included in the report by clicking here* . This way, we can ensure the support and accommodations that you deserve. **If you do not yet have the assessment, don't worry: we can support you in obtaining it. We have a dedicated Health and Well\-being team, inclusion specialists, and affinity groups who will be with you at every stage. Count on us to make this journey side by side.******************************************************