Senior .NET Backend Developer

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.