Sergiy S.Private profile: Upwork shows its earnings only to signed-in members, so we check it every few weeks, not daily. MRR here is a rough estimate (Upwork's six-month earnings ÷ months active). Last read Nov 5, 2026.

Frustrated with freelancers who cause more problems than they solve? Development delays, endless bug fixes, and wasted budgets can stall your project’s success. You deserve better - and you've just found the right partner. I am a Senior Full-Stack & Integration Engineer with 14+ years of experience architecting scalable backend systems, custom API integrations, and automated workflows. How I can help your business: • System Integration & APIs: Connecting disparate SaaS platforms, building custom REST/GraphQL APIs, Webhooks, and data pipelines. • Custom Backend & SaaS: Engineering robust, high-availability architectures using Node.js, Python, and PHP. • Database & Performance Optimization: Designing scalable PostgreSQL/MySQL schemas, async processing, and system refactoring. My focus is on creating systems that are easy to maintain, expandable for future growth, and thoroughly tested to minimize bugs from the start. When you hire me, you’re investing in top-tier quality, reliability, and a real commitment to your project's success. Have a complex integration or backend challenge? Let's discuss your project!