Senior Fullstack C# and React Engineer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Fullstack C# and React Engineer based in Brazil. Join a fully remote engineering team building scalable B2B SaaS solutions for global clients in a fast-paced, cloud-native environment. In this hands-on role, you will own application and service development from architecture and implementation through testing and deployment. You’ll work primarily across C#/.NET and React, with a backend-leaning focus and approximately 70% hands-on development and 30% mentoring. Your work will involve microservices, APIs, event-driven architectures, cloud platforms, and modern infrastructure. You’ll collaborate across teams, influence technical decisions, and help deliver reliable, secure, and high-performing solutions. This is an opportunity to combine deep technical execution with leadership and meaningful impact. Accountabilities Develop and maintain scalable applications and services using C#/.NET and React, primarily hosted on AWS and/or Azure PaaS environments. Design technical architectures using diagrams and detailed technical design documentation, translating functional and non-functional requirements into reliable solutions. Build highly available, scalable, and cost-efficient microservices and modern APIs within distributed software architectures. Design and implement event-driven solutions that enable system components to communicate and trigger actions efficiently. Work with Docker, Terraform, NoSQL databases, and distributed storage technologies to support modern cloud-native applications. Integrate security practices throughout the software development lifecycle and ensure solutions meet appropriate security standards. Implement monitoring and observability solutions to track application performance, system health, and resource utilization. Estimate and plan development work through user stories and technical tasks, delivering independ