UKAOBASI CALLISTUS

I’m a Full-Stack Software Engineer with 6 years of experience building scalable web applications, backend systems, and cloud-native solutions across fintech, SaaS, and AI-driven products. I focus on system design, API development, database optimization, and performance engineering that improves scalability, reliability, and response times in production.

Most recently, I built a production RAG-based AI support system with a React-based management console, delivering 3–4s response times using asynchronous processing and near-instant client acknowledgments. I reduced LLM API costs by 62% through multi-layer caching, query optimization, and request deduplication, and I designed a distributed event-driven architecture using AWS Lambda and SQS.

I’ve also delivered real-time and high-throughput backend systems—architecting modular REST APIs in NestJS and implementing WebSockets for live updates and event-driven interactions. With Redis caching and database tuning, I achieved sub-100ms response times on critical endpoints and strengthened delivery through Docker + Jenkins CI/CD for zero-downtime deployments.

I take ownership of production systems with a strong focus on scalability, reliability, and trade-offs. I communicate technical ideas clearly across teams, proactively resolve issues, mentor others, and align engineering decisions with product and business goals.