Süleyman Kayabaşı

Sole backend engineer in a cross-functional squad, owning 12 microservices end-to-end — architecture, implementation, deployment, and production support Led Java/Spring Boot and Elasticsearch upgrades across all services, rewriting the query layer to fix breaking API changes Redesigned the coupon filtering system with multi-dimensional filters, improving user targeting and engagement Designed a risk-tiered coupon recommendation algorithm, balancing odds ranges, deduplication, and bet structure rules

Contributed to the migration from monolith to microservices, improving uptime and release velocity Built reactive payment services (Java, Kotlin, Spring WebFlux/Reactor), cutting average API latency by ~30% under peak load Implemented integrations for card payments, digital wallets (Masterpass/BKM), and bank transfers, including installment payment flows Achieved 90% unit test coverage and strengthened CI/CD pipelines

Enhanced executive dashboards in the loan approval workflow for a bank subsidiary Assisted with legacy code refactoring and critical production bug resolution under senior engineer guidance

Gained hands-on exposure to backend development practices and tooling during a 4-month internship Supported the team with development and testing tasks as part of a Computer Engineering internship program