Built and deployed RESTful APIs (user profiles, string analysis, country data, wallet operations). Integrated third-party APIs (cat facts, country data, exchange rates, Paystack). Implemented JWT authentication, API keys, secure transaction handling, wallet services with Paystack, and AI agent integrations. Worked on microservice-style backend APIs and contributed to the HNG Job Portal. Reviewed code and supported other backend developers; collaborated with frontend, product, and DevOps teams.