sergiishapoval

Own backend delivery for billing, metering, and payment-method workflows, improving delivery continuity in a dependency-heavy domain. Owned GCP / AWS Marketplace payment-method integration from design documentation and epic breakdown to implementation scope for pricing and reporting. Delivered direct payment-method enhancements for credit card, ACH, and wire transfer flows with Stripe integration, broadening payment support coverage. Built and evolved service contracts and interactions using Go, gRPC, Protobuf, Temporal, and event-driven messaging, improving service boundary clarity. Improved production supportability by adding OpenTelemetry traces, Prometheus alerts, Grafana dashboards, and runbooks, enabling faster incident triage. Investigated third-party billing dependency risks, documented alternatives, and introduced earlier validation practices to reduce blocker-driven delays. Coordinated execution across Product, Finance, Cloud Platform, Support, and two backend engineers, improving cross-team alignment and delivery readiness.

Built transaction-driven backend capabilities in personal-finance systems, enabling more targeted product-trigger flows from user events. Implemented and maintained Kafka-based notifier services with scheduled and batch delivery via Mandrill, improving multi-service communication reliability. Resolved long-standing authentication issues and reworked security-related flows, strengthening access control and login stability. Profiled and fixed memory leaks, and improved release/testing workflows to increase production confidence.

Built and optimized REST/SOAP integrations, persistence models, and schema migration flows in Java backend environments. Delivered integration-heavy backend and tooling work (OAuth2 clients, data-processing flows, and technical documentation support) that strengthened system and domain fundamentals. Early product-facing role experience improved stakeholder communication, requirements framing, and business-context decision making.