Roman

ROMAN SAPUN
AI Developer · Python & LLM Systems
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Warsaw, Poland

Summary
AI-focused Python developer with 1.5+ years building production backends, LLM-powered systems, and automation pipelines
on Linux. I take problems end-to-end: understand the requirement, prototype quickly, ship a working system, and improve it
from feedback. Builds LLM agents and RAG pipelines with the OpenAI and Anthropic (Claude) APIs, LangChain, and
LangGraph, alongside backend engineering across FastAPI, Django, PostgreSQL, async task queues, and WebSockets.
Works in a team with regular code reviews, focused on AI-driven product engineering.

Skills
AI & LLM: LLM APIs (OpenAI, Anthropic / Claude), LangChain, LangGraph, MCP (Model Context Protocol), AI agents, RAG,
NLP, ChromaDB, speech-to-text (Whisper), text-to-speech, prompt engineering, evaluation
Languages: Python 3.12, SQL, JavaScript, TypeScript, HTML/CSS, Java, React
Backend & async: FastAPI, Django REST Framework, Litestar, SQLAlchemy, Alembic, asyncio, TaskIQ, Celery, RabbitMQ,
WebSockets
Databases & caching: PostgreSQL, Redis, MongoDB, MS SQL, SQLite
DevOps & cloud: Docker, Kubernetes, AWS (EC2, RDS, S3), GitLab CI / GitHub Actions, Linux, Nginx
Tools: Playwright, Postman/Insomnia, unit/integration/e2e testing, Jira, Kanban

Languages
English Upper-Intermediate Polish Upper-Intermediate

Experience
DevPower 12/2025 - Present
AI / Python Backend Developer
• Built AI agents for content moderation and quest verification (LLM APIs + WhisperAI), cutting manual review workload by
70% while maintaining quality.
• Shipped LLM-powered features end-to-end with the OpenAI and Anthropic (Claude) APIs, LangChain, and LangGraph,
including prompt design, tool orchestration, and output evaluation.
• Built an automatic proxy-bidding engine (eBay-style) for an auction marketplace: auto-resolves bidding wars up to each
bidder's maximum to a second-price result and reconstructs the full bid history, with anti-sniping time extensions, buy-now,
and reserve-price handling; ran asynchronously on TaskIQ + RabbitMQ for 200+ concurrent users.
• Introduced structured JSON logging with request tracing and error categorisation, cutting production-incident debugging
time by 60%; 85% integration test coverage.
Freelance 04/2025 - 11/2025
Python / AI Developer
• Built and deployed an AI-powered mock-interview web app: voice interviews with Whisper speech-to-text and Microsoft
Edge neural text-to-speech, LLM-driven role-specific question generation and automated answer feedback (live demo).
• Built a RAG system (ChromaDB vector store) for semantic search across 500+ technical articles, with chunking, an
embeddings pipeline, and retrieval-quality evaluation.
• Designed and implemented a Django + DRF REST API with JWT auth, role-based permissions, pagination, and
integration tests.
Freelance 01/2024 - 05/2024
Python Backend Developer
• Built a FastAPI microservice for async order processing (Celery + RabbitMQ) for an e-commerce client, speeding up order
confirmation.
• Integrated AI features into the client's admin panel, auto-generating product descriptions and metadata and cutting the
manual work of adding new products.
• Built FastAPI and Django services with PostgreSQL (REST and GraphQL APIs, data-pipeline integration), and diagnosed
production issues across several unfamiliar client codebases, getting up to speed quickly under tight deadlines.

Education
Społeczna Akademia Nauk Łódź, Poland
BSc, Software Engineering / Computer Science 09/2021 - 03/2025

Mate Academy Online
Python Development course (certificate) 11/2025