Denys H.

I build and improve production Python backends where performance, reliability, and integration complexity matter. 10+ years in backend engineering across fintech, energy trading, B2B travel, and SaaS, with hands-on experience designing distributed systems, high-throughput pipelines, APIs, and data-intensive services. Selected results: * Increased event-processing throughput by 267%, from 150K to 550K events/hour * Reduced execution time of a core financial computation engine by up to 3x * Designed Kafka-based data pipelines for automated ingestion, processing, and real-time result delivery * Built memory-efficient streaming processing for multi-GB datasets * Delivered integrations with payment systems, booking providers, risk engines, and enterprise platforms I work primarily with: Python / FastAPI / Django / Flask PostgreSQL / MongoDB / Redis Kafka / RabbitMQ Apache Airflow / PySpark Docker / Kubernetes AWS / GCP / Azure integrations Typical problems I can take ownership of: * Backend architecture and system design * API and microservice development * Performance and database optimization * Event-driven and asynchronous systems * Data pipelines and integrations * Legacy Python modernization and refactoring * Production debugging and reliability work * Architecture and codebase reviews I am most useful on systems that have already moved beyond the prototype stage and need experienced engineering judgment: architecture decisions, production reliability, performance, maintainability, and integration with existing infrastructure.