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Maciej – Python, LLM, OpenAI, experts in Lemon.io

Maciej

From Poland (UTC+2)

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Back-end Web DeveloperSenior
AI EngineerMiddle-to-senior
9 years of commercial experience
Adtech
Advertising
Biotech
Cybersecurity
Entertainment
Healthtech
Manufacturing
Marketing
Media
Pharmaceutics
AI software
Customer support software
Helpdesk software
Software development
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Maciej – Python, LLM, OpenAI

Maciej is a thoughtful and pragmatic Backend Python Engineer with 8 years of experience building robust, scalable applications and APIs using Python, Django, and FastAPI. Over the past two years, he has been actively expanding his expertise into AI and LLM-powered applications, making him a valuable bridge between solid backend architecture and cutting-edge AI solutions. In the AI space, he’s built multi-agent systems and tool-augmented LLMs with a strong focus on security and reliability. Maciej is articulate, quick to learn, and solves problems pragmatically. He’s a proactive, collaborative engineer who strengthens any team with clean, efficient solutions that connect backend systems with modern AI.

Main technologies
Python
8 years
LLM
3 years
OpenAI
3 years
Additional skills
Django
FastAPI
Prompt engineering
LangChain
Microsoft Azure
AWS
Web scraping
Chroma
Azure DevOps
RAG
Redis
OpenAI API
Django REST
Google API and Services
pytest
PostgreSQL
Docker
ArangoDB
Grafana
React
Typescript
D3.js
Selenium
Playwright
Pydantic
GCP
Firestore
Direct hire
Possible
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Experience Highlights

Senior AI & Backend Engineer
Feb 2025 - Ongoing4 months
Project Overview

Development and enhancement of an AI-powered chatbot tool designed to assist customer service agents in providing efficient and accurate support for diagnostic instruments. The tool helps automate routine inquiries, offers real-time recommendations, and improves response quality, ultimately supporting smoother troubleshooting and better customer experience within the healthcare diagnostics domain.

Responsibilities:
  • Refactored POC to Clean Architecture, decoupled 3rd-party dependencies, implemented test suite and quality checks;
  • Built AI copilot with RAG for 500+ users on Azure;
  • OpenAI/Langchain/Langraph for Roche diagnostic troubleshooting;
  • Developed intelligent agents with tool-calling for multi-step support workflows;
  • Led monolith-to-microservices refactoring with frontend/backend separation;
  • Improved copilot accuracy through prompt engineering workshops with domain experts;
  • Increased test coverage 40% → 80% with TDD and CI/CD quality gates;
  • Conducted 6+ AI workshops on Cursor/Copilot, boosting team productivity;
  • Mentored junior engineers on clean architecture and AI best practices.
Project Tech stack:
Python
Microsoft Azure
OpenAI
LangChain
OpenAI API
LLM
RAG
Chroma
FastAPI
Azure DevOps
Jira
Clean Architecture
Redis
Senior Backend Engineer
Feb 2025 - May 20253 months
Project Overview

A centralized REST API solution that connects an Airtable database with major advertising platforms (Meta, Google, TikTok) to enable automated creation and management of ad campaigns. The project aims to eliminate repetitive manual tasks for media buying teams, ensuring faster campaign launches, improved data consistency, and better scalability across multiple marketing channels.

Responsibilities:
  • Solo-architected automation platform integrating Airtable, Meta, Google Ads, and TikTok APIs, reducing campaign creation from hours to instant;
  • Built an extensible Django REST API with a provider pattern for easy platform additions and event-driven Celery tasks;
  • Implemented a comprehensive test suite with 90% coverage, including unit and integration tests;
  • Deployed on AWS with enterprise security, rate limiting, and API documentation;
  • Created extensive technical documentation and conducted knowledge transfer sessions with the company's full-time developer for a smooth handoff.
Project Tech stack:
Python
AWS
CloudWatch
Django
Django REST
Celery
Redis
asyncio
Integration testing
Unit testing
API
Facebook SDK
Google API and Services
Google Ads
Cloud Architecture
Senior Backend Engineer
Aug 2024 - Jan 20255 months
Project Overview

A specialized software solution designed to manage, maintain, and optimize Change of Line (CoL) processes within pharmaceutical manufacturing laboratories. The project aims to streamline production line adjustments, ensure compliance with industry standards, and enhance overall operational efficiency by automating routine tasks and providing robust monitoring and reporting capabilities.

Responsibilities:
  • Implemented async Django features, reducing API response times;
  • Optimized critical API endpoint, cutting latency across the enterprise application;
  • Reduced CI/CD build times through Docker optimization;
  • Introduced type hints and async patterns to a large Python codebase.
Project Tech stack:
Python
FastAPI
Docker
Celery
ArangoDB
PostgreSQL
OpenAI
pytest
Backend Engineer
Nov 2022 - Aug 20241 year 9 months
Project Overview

A large-scale platform providing global edge cloud services, a high-performance content delivery network (CDN), and secure hosting solutions. The project focuses on delivering low-latency content distribution, reliable cloud infrastructure, and scalable hosting to support businesses in optimizing their online presence and performance worldwide.

Responsibilities:
  • Built a unified logging package deployed across 6 microservices (2 Django, 4 FastAPI);
  • Developed statistics API processing traffic data for real-time dashboards;
  • Integrated ML content moderation models via REST API;
  • Set up Grafana monitoring with health and performance dashboards;
  • Introduced OpenAI and CodeRabbit for automated code reviews.
Project Tech stack:
Python
Django
Django REST
FastAPI
Celery
OpenAI
OpenAI API
Cloud Computing
Cloud Architecture
Software design
Integration testing
Unit testing
PostgreSQL
Grafana

Languages

English
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