This position is listed on behalf of a partner company, which manages all applications and next steps. Our partner is looking for a Desenvolvedor C# - Sênior based in Brazil. We are looking for a Senior C# Developer to design, develop, maintain, and optimize critical backend systems supporting health insurance providers. In this role, you will build and integrate APIs, improve application performance, and ensure the reliability and stability of essential business systems. You will contribute to database modeling, query optimization, and the resolution of complex technical issues. Working in an agile, collaborative environment, you will also help translate business needs into technical requirements and actionable development tasks. This is an opportunity to make a meaningful impact through robust software solutions while contributing to continuous improvement and technical excellence.