Oleksii Vasylenko is a hands-on Technical Lead and Systems Engineer who helps teams solve demanding engineering challenges and bring ambitious products to scale. Based in Brazil (UTC−3), he works remotely in full-time or contract roles, combining technical direction, team leadership, and implementation.

His expertise includes matching engines, distributed systems, durable workflow engines, performance engineering, and frontend architecture. At Bitsten, he architected an exchange matching engine capable of processing more than 4,000 orders per second with sub-millisecond latency, alongside market-data and order-book improvements. At PropertyGuru, he helped four product teams move from a shared frontend monolith to independent deployments, building a unified payment service that reduced release cycles from weeks to days.

Vasylenko has led 15 engineers across three time zones and has experience with Node.js, PostgreSQL, Redis, React, and TypeScript. His work also includes a multi-blockchain zk-SNARK wallet engine and independent engineering research on durable execution. He partners with organizations to identify bottlenecks, improve reliability, clarify team ownership, and deliver complex systems from architecture through production.