Senior .NET Backend Developer
CI&T
At CI\&T, we help large enterprises transform the potential of AI into real business impact with AI Deployment, AI\-native execution, and tech\-integrated business solutions. With 30 years of experience in technological transformation, we accelerate innovation with expertise in Agentic SDLC, Application modernization, Data \& AI, Martech and Business strategy. We are 8,000 CI\&Ters across more than 25 countries, collaborating to build solutions with real impact. AI is already part of how we work, evolve, and innovate every day. At CI\&T, we are looking for a skilled and motivated Senior .NET Backend Developer to join one of our delivery teams. You will design, build and evolve scalable, secure and maintainable backend services using a modern .NET stack, working closely with Product, Architecture, QA and Frontend colleagues in a collaborative, multicultural and fast\-moving environment. Your responsibilities * Design, develop and maintain RESTful APIs and backend services using C\# and .NET 8\+. * Apply Clean Architecture, SOLID and KISS principles to keep code modular, reusable and simple. * Build event\-driven and asynchronous integrations using messaging platforms such as Azure Service Bus, RabbitMQ or Kafka. * Model, query and optimize relational databases such as PostgreSQL and SQL Server, using Entity Framework Core. * Work with document databases such as MongoDB, when needed. * Implement secure authentication and authorization using OAuth2/OIDC and JWT. * Write and maintain automated unit and integration tests using tools such as xUnit, NSubstitute and Bogus. * Contribute to CI/CD pipelines, including Azure DevOps and YAML pipelines, and follow agreed branching strategies such as GitFlow. * Instrument services for observability, including structured logging, metrics and tracing, and help diagnose production issues. * Critically read, validate and review code, including code generated by AI tools, to uphold quality, security and performance standards. * Take part in code reviews, technical refinement and estimation, and help mentor less experienced developers. * Work with technical and non\-technical stakeholders to turn requirements into pragmatic, maintainable solutions. Requirements for this challenge * Solid experience as a backend developer working with C\# and .NET, ideally .NET 8\+, including production\-grade RESTful APIs. * Strong knowledge of object\-oriented design, SOLID principles, design patterns and Clean Architecture. * Hands\-on experience with MediatR, AutoMapper and Entity Framework Core. * Experience with relational databases such as PostgreSQL or SQL Server, including data modelling and query optimization. * Experience with distributed systems and messaging, using technologies such as Azure Service Bus, Rebus, RabbitMQ, Kafka or equivalent. * Practical use of AI tools in software development, such as GitHub Copilot, Claude, OpenAI APIs or similar, including AI\-assisted code generation, testing and refactoring. * Experience building autonomous or semi\-autonomous agents for software development, or knowledge of prompt engineering and evaluating AI output quality. * Experience with automated testing, including unit and integration testing and the use of test doubles. * Working knowledge of Docker and Docker Compose. * Familiarity with observability tools such as Datadog, Grafana, Application Insights or the ELK Stack. * Experience with Git, CI/CD pipelines and Azure DevOps, or similar tools. * Good communication skills and a collaborative, ownership\-driven mindset. * Good spoken and written English (upper\-intermediate or above). Nice to have * Knowledge of CQRS and Domain\-Driven Design (DDD). * Experience with MongoDB, including document modelling and aggregation. * Knowledge of Infrastructure as Code, using technologies such as Terraform, Bicep or ARM. * Exposure to a frontend framework such as React, Angular or Vue, including API integration from the client side. * Experience working in polyglot environments, such as Node.js, Python or Java. \#midsenior **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 y