Nisa I.

I help fintech and SaaS teams build, stabilize, and modernize Java backend systems using Java 17/21, Spring Boot, microservices, Kafka, and PostgreSQL. I specialize in production APIs, legacy modernization, and complex enterprise workflows. I can help with: • Java 17/21 and Spring Boot REST APIs • Microservices and event-driven architecture with Kafka • Legacy Java/JBoss modernization • PostgreSQL, JPA and Hibernate query optimization • Spring Security, JWT, OAuth2 and role-based access control • Payment, banking and financial workflow integrations • Production debugging, refactoring and automated testing • Docker, Kubernetes and AWS deployments I am most useful when a backend has become slow, difficult to maintain, or risky to change. I can investigate the current architecture, identify the actual bottleneck, propose a practical remediation plan, and implement the agreed changes without unnecessary rewrites. Recent experience includes financial transaction systems, approval workflows, SaaS platforms, real-time dashboards, and multi-service backend modernization. My deliverables normally include clean source code, automated tests, API documentation, database migration scripts where required, and a clear handover for your engineering team. Send me the current issue, architecture, or repository context, and I will outline the first investigation steps before we begin.