# Sergiy Mirochnyk **Senior Full-Stack Engineer & AI / LLM Engineer** Dijon, FR · French citizen — full right to work in the EU/EEA and Switzerland, no visa or sponsorship required · remote / hybrid / on-site in Dijon mirochnyk.sergiy@gmail.com · +33 7 54 38 67 68 · [GitHub](https://github.com/SergeMiro) · [LinkedIn](https://www.linkedin.com/in/sergemiro) · [Website](https://smiro.dev) _Also answers to: Senior Full-Stack Engineer · Full-Stack Developer · AI Engineer · LLM Engineer · Software Engineer · Ingénieur Full-Stack Senior · Développeur Full-Stack · Ingénieur IA._ ## Summary Senior full-stack engineer with 9 years of production web development (2017 to present), taking applications end to end: interface, API, database, deployment and monitoring. Core stack React, Next.js, TypeScript, Node.js and Python with PostgreSQL and SQL Server. Applied AI in production since 2023: multi-agent systems with executor/reviewer loops, RAG over company data, LLM fine-tuning on self-hosted GPU servers, and n8n automation — with tests, evaluations, monitoring and cost controls around them. Six years in IT systems and network security before that. Provisions, secures and operates what he ships: Linux VPS, Docker, Nginx, CI/CD and monitoring. ## Skills **AI & LLM Engineering** — _Core — shipped in production_ Multi-agent systems · RAG · Prompt engineering · Executor / reviewer loops · LLM fine-tuning · LoRA · QLoRA · Unsloth · Model routing & cost control · Evaluations & guardrails · OpenAI API · Anthropic Claude API · Self-hosted Llama · Self-hosted Mistral · Embeddings · pgvector · Qdrant · n8n **AI-Assisted Development** — _Core — daily_ Claude Code · MCP servers · Spec-driven delivery · Cursor · GitHub Copilot · Agent orchestration · Reviewer gates before merge · Runtime verification **Frontend** — _Core_ React · Next.js · TypeScript · JavaScript · Zustand · Tailwind · Astro · HTML5 · CSS3 **Backend & Data** — _Core_ Node.js · Express · Python · FastAPI · REST APIs · Celery · Redis · PostgreSQL · SQL Server · T-SQL · Supabase · Row-Level Security · Jest · Git · GitHub **DevOps · AI-Ops · Security** — _Core_ VPS provisioning & deploy · Docker · Traefik · Linux · Nginx · CI/CD · Self-hosted GPU servers · Grafana · Metabase · OWASP · Auth, RBAC & Row-Level Security · Firewall & network security **Working knowledge** — _Used, not yet shipped professionally_ Redux · LangChain · LangGraph · CrewAI · PyTorch · Hugging Face · WebSockets ## Professional Experience ### Full-Stack Developer & AI Engineer — FIMAINFO (Software development & cloud solutions) Sep 2023 – Present · Dijon, France Full-stack delivery and the company's applied-AI practice: multi-agent systems, RAG over internal knowledge, self-hosted LLMs, and back-office automation. - Designed and shipped multi-agent AI systems for call-centre campaigns: an executor agent does the work, a reviewer agent scores it, and the loop repeats until the score reaches 90%. Cut back-office work by ~80% — about 30 hours a week per team covered. - Built RAG search over internal business knowledge and exposed company data to agents through MCP-style tools and REST APIs, with per-role access control (RBAC). - Delivered full-stack internal products end to end: responsive React / Tailwind interfaces, Node.js / Express APIs, SQL Server / T-SQL across four estates, Jest tests, CI/CD and production deployment. - Fine-tuned open-weight LLMs and served them from in-house GPU servers behind REST APIs — data stays on company hardware and token spend drops; added routing between light and heavy models. - Automated recurring back-office with n8n: email parsing, ticket routing, invoicing, compliance filings, notifications. Added monitoring, SLA alerting and anomaly detection. - Introduced an AI-assisted development workflow with spec-driven prompts and reviewer gates before merge — shorter cycles without giving up code review, tests or OWASP checks. _Stack: multi-agent systems, RAG, OpenAI API, Anthropic Claude API, embeddings, pgvector, Qdrant, MCP, React, Tailwind, Node.js, Express, SQL Server, T-SQL, Jest, CI/CD, Unsloth, LoRA, QLoRA, Llama, Mistral, GPU servers, n8n, Grafana, Metabase, Claude Code, Cursor, GitHub Copilot, OWASP._ ### Web Developer — Novileads Co. Aug 2022 – Aug 2023 · Ukraine — remote - Built responsive marketing sites and web applications from Figma mockups, and shared component libraries with the back-end developers and designers. - Front-end performance and cross-device compatibility; technical SEO and Core Web Vitals checked on delivery. _Stack: HTML5, CSS3, JavaScript, Figma, technical SEO, Core Web Vitals._ ### Web Developer — French Foreign Legion (Képi Blanc magazine & other Legion sites) May 2017 – May 2021 · France - Built and maintained site components for Képi Blanc magazine and other Legion sites; ran the content with the editorial team, plus technical SEO, social integrations and performance work. _Stack: HTML, CSS, JavaScript, CMS, technical SEO, performance._ ### IT Technician — French Foreign Legion (1st R.E.G. / 1st R.E.) Oct 2011 – May 2017 · France - Installed, configured and maintained hardware and software fleets for operational units, with L1/L2 support for their users. - Network security: firewall and antivirus administration, system hardening. _Stack: network security, firewall, antivirus, system hardening, L1/L2 support._ ## Projects ### LLM Failover Proxy — open source · npm · 2026 One OpenAI-compatible endpoint that switches model when a provider fails, rate-limits or slows down — without breaking a live stream. 12 commits and +1,638 lines merged upstream, published as v1.8.0. _Stack: Node.js 22, SSE, OpenAI-compatible API, provider adapters, zero runtime dependencies._ ### Extranet Fimainfo — work · internal platform · 2026 One internal platform for telephony, campaigns, messaging, BI and an AI assistant: 5 services, ~60 screens, 4 SQL Server estates, ~786 commits over 17 months. _Stack: Next.js 15.5, React 19, Zustand, Express, SQL Server, FastAPI, Qdrant, RAG, RBAC._ ### ASCoFaçade — production · client · 2026 Public SEO site and 4 role portals behind one login — office, clients, sub-contractors, field crews — plus 3 AI jobs, none of them a chatbot. _Stack: Next.js 16, React 19, Supabase, Row-Level Security, Server Actions, Vercel, Tailwind 4._ ### SimplifyEU — AI back-office · 2026 Finds duplicate invoices, unused subscriptions and missed deadlines across 4 Python services. _Stack: Next.js 16, FastAPI, Celery, Redis, Docker, Traefik._ ### Way2Buy Mini App — telegram · product · 2026 Telegram Mini App for sales, cashback, discounts, margin tracking and AI reports. _Stack: Node.js, Express, SQLite, Telegram Mini Apps, idempotent jobs, 81 tests._ ### Earnings trading bot — research lab · 2026 Personal multi-agent lab for earnings research, scoring and fixed risk rules. Not financial advice. _Stack: Python 3.12, SQLAlchemy 2, APScheduler, Docker, multi-agent._ ### smiro.dev — personal · site & AI avatar · 2026 This site: portfolio, CV, a live agent playground and an AI avatar that answers questions about the work from a generated knowledge base. _Stack: Astro, TypeScript, Vercel, RAG, n8n, Playwright, Linux VPS._ ## Education - **JavaScript / React Application Developer** — RNCP Level 6 (Bachelor-equivalent), OpenClassrooms (Aug 2021 – Aug 2022) · France - **Business Informatics — information systems & databases** — 4-year university degree, University (Ukraine) (Sep 2007 – Aug 2011) · Ukraine ## Certifications - JavaScript / React Application Developer — RNCP Level 6 (Bachelor-equivalent) · Aug 2022 — France Compétences — RNCP / OpenClassrooms - University Degree — Business Informatics (4-year) · Aug 2011 — University (Ukraine) - Unsloth — open-source LLM fine-tuning (LoRA / QLoRA) — Self-directed ## Languages - **French** — C2 — professional - **Ukrainian** — Native - **Russian** — Native - **English** — B2 — technical --- Last updated 2026-09-07. 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