Yaroslav N.

Senior Python, Go, React and AI engineer who builds and scales SaaS products: backends and APIs, AI agents and LLM features, integrations and cloud infrastructure. Recent work includes accounting and fintech platforms with QuickBooks, Xero and Sage integrations. On Jenesys AI, I helped grow the platform from 5 to 130+ firms and improved its performance by 30%. I can also lead your team as a tech lead or fractional CTO. Track record - 8+ years on Upwork, $700K+ earned, Top Rated Plus, 30+ contracts - AWS certified, with experience on HIPAA projects - Took Jenesys AI from v0 to v1 and grew it from 5 to 130+ accounting firms What I've built - Jenesys AI: an AI bookkeeping platform for accounting firms, with a multi-tenant backend, AI document processing and syncs with QuickBooks, Xero and Sage - DealSheets: revenue recognition and reporting for a financial SaaS, with ARR, churn and revenue-forecasting dashboards - Deepchecks: backend services for an LLM evaluation platform that tests and monitors AI models in production - Event-driven pipelines on AWS processing millions of records - Booking and marketplace platforms with payments, CRMs and many third-party APIs How I can help - Build an MVP and take it to production - Take over an existing codebase and make it stable - Add AI agents and LLM features (OpenAI, Claude, LangChain) with tool calling and proper testing - Connect payment, accounting and CRM systems so syncs don't break or double-post - Part-time technical leadership: architecture, code reviews and hiring - Take a role of Fractional CTO How I work: I take ownership, flag risks early, and write clean, tested code your team can build on. Stack: Python (FastAPI, Django, Flask and more), Go, Node.js, Laravel · React, Next.js, TypeScript · OpenAI, Claude, LangChain/LangGraph · AWS (Lambda, ECS, SQS), GCP, Docker, Kubernetes, Terraform · PostgreSQL, Redis, Kafka Send me your goal, your current stack and what isn't working, and I'll tell you honestly how I'd approach it.