Senior Backend Developer

Description

**Senior Backend Developer** We are looking for a **Senior Backend Developer** to drive people and businesses forward through innovation—with attitude, leadership, and a focus on getting things done. **Your impact in this role:** Work on analysis, re-engineering, conversion, and maintenance of existing API modernization in the AS-IS environment, supporting migration to the TO-BE model—with emphasis on preserving business rules, technical quality, interoperability, documentation, and testing. The professional will be responsible for understanding existing APIs and integrations, identifying legacy behaviors, mapping contracts, business rules, and technical dependencies, and implementing new interface versions according to the architectural standard defined for the future environment. Analyze and assess how APIs function in the current environment. Perform reverse engineering of legacy services when required. Map existing business rules, integrations, dependencies, and contracts. Develop or rewrite APIs according to the standard defined for the future environment. Adapt or rebuild integrations between systems and databases. Ensure functional compatibility between AS-IS and TO-BE behaviors. Create and maintain technical documentation for migrated APIs. Design and execute unit, integration, and technical regression tests. Support API-consuming teams during acceptance testing and stabilization. Handle fixes, troubleshooting, and incident analysis related to conversion. Participate in technical decisions, backlog refinement, and prioritization for modernization. Support identification of technical migration risks and propose mitigation alternatives. **Stack:** Java SQL Server Oracle ColdFusion Sybase ✅ **Essential Requirements:** Solid backend development and system integration experience. Experience with Java for building and maintaining APIs. Experience with REST APIs, JSON, HTTP, authentication, and service versioning. Hands-on experience with evolutionary maintenance and ongoing support of legacy systems. Experience analyzing existing code and understanding embedded business rules. Knowledge of relational database modeling and manipulation. Experience with SQL Server. Experience reading, analyzing, or integrating with Oracle databases. Knowledge of API testing practices. Ability to produce technical documentation for contracts, workflows, and integrations. Experience with version control and software development best practices. Analytical profile capable of operating both at the technical layer and in functional understanding of interfaces. * **Nice-to-Have:** Prior experience in legacy system modernization. Knowledge or experience with ColdFusion. Knowledge or experience with Sybase. Experience in database migration scenarios. Experience with modern Java frameworks such as Spring Boot. Experience defining or consuming OpenAPI/Swagger specifications. Experience with CI/CD pipelines. Knowledge of messaging, API security, and observability. Familiarity with service-oriented architecture and enterprise integration. Experience in projects involving high-volume integrations and high criticality. Relevant differentiators include experience in projects involving: * large-scale API conversion, * transition from legacy to modernized architecture, * extraction of business rules from source code and databases, * stabilization of integrations post-migration. **Benefits:** Remote work allowance Flash card Access to South Academy courses and certifications Financial education program Total Pass — Well-being **About South:** You’ll join a collaborative team that values autonomy and continuous improvement—working on projects with real business impact, where turning ideas into deliverables is part of everyday life. We’re recognized for our people: we’ve been named twice among the best companies to work for in Brazil (GPTW). We’re committed to the future: we’re a carbon-neutral company. Interested? Apply now and help us make it happen.