v
vitalii_lysenko

Vitalii L

@vitalii_lysenko

Senior Backend and AI Engineer Python, RAG, FastAPI, Laravel, API

Ukraine
Ukrainian, English
About me
Senior Backend & AI Engineer (8+ years). I bridge the gap between Modern AI and Enterprise Web. đŸ€– AI & Python: I architect custom RAG microservices, LLM agents, and async systems using Python, FastAPI & pgvector. I build smart Corporate Knowledge Bases that eliminate hallucinations. ⚙ Enterprise APIs: Deep expertise in PHP/Laravel, building high-load CRMs and complex integrations (Payments, Web3/TRC-20). I design robust, scalable architectures from scratch. Let's build something great!... Read more

Skills

v
vitalii_lysenko
Vitalii L
Offline ‱ 

See my services

Bug Fixes
I will fix laravel bugs, 500 server errors, and database issues
From$50 / projectMore details
AI Integrations
I will build custom ai chatbot, rag system, and openai API integration
From$100 / projectMore details

Portfolio

Work experience

Freelance

Senior AI Backend Engineer

Freelance ‱ Freelance

Aug 2026 - Present ‱ 2 mos

Designed and developed a production-ready Open-Source Corporate Knowledge Base (RAG microservice) from scratch. The engine functions as a smart search system, allowing AI to accurately answer questions based purely on internal corporate documentation. ‱ Built a fully asynchronous architecture to ensure high throughput and low latency. ‱ Implemented vector search using PostgreSQL with the pgvector extension for efficient document retrieval. ‱ Engineered semantic query caching to significantly reduce OpenAI API costs. ‱ Enforced strict context boundaries to guarantee zero LLM hallucinations. The core architecture is open-sourced to demonstrate code quality and system design. Link provided in my profile. Used technologies: Python, FastAPI, AsyncIO, PostgreSQL, pgvector, OpenAI API, Docker. The core architecture is open-sourced to demonstrate code quality and system design. GitHub Repository: https://github.com/VitaliiLysenkoo/rag-support-api Used technologies: Python, FastAPI, AsyncIO, PostgreSQL, pgvector, OpenAI API, Docker.

Software_Development

Senior Full Stack Engineer

Software Development ‱ Full-time

Dec 2022 - Jul 2026 ‱ 3 yrs 7 mos

Developed complex CRM systems and REST APIs using Laravel 10 and Vue 3. Successfully integrated multiple third-party services and AI agents (OpenAI API) to automate business processes. Optimized database performance (MariaDB, Redis) for high-load workflows.

Software_Development Company, Mobile App & Web Development Service

Backend Engineer

Software Development Company, Mobile App & Web Development Service ‱ Full-time

Nov 2022 - Nov 2023 ‱ 1 yr

Built and optimized backend architectures for marketplaces. Designed secure REST APIs for React/Vue frontends. Key achievement: Integrated the Tron Network API to verify transactions, generate TRC-20 wallets, and process cryptocurrency payments seamlessly.