Senior Backend System Engineer (Python / FastAPI)

Teamtailor; Warszawa; On-site; PLN 253,000 - 339,000; Full time

Job summary

A cutting-edge tech company in Warsaw is seeking an experienced backend engineer to build a robust backend and revamp their platform. You will audit and design scalable systems, refactor existing modules, and collaborate directly with the CTO. Ideal candidates have over 6 years of experience with Python and FastAPI and a background in data processing. Full-time preferred, but part-time can be considered.

Qualifications

• 6+ years of solid backend and systems design experience.
• Expert-level skills in Python and FastAPI.
• Proven experience structuring data processing or machine learning pipelines.

Responsibilities

• Audit and review an existing Python/FastAPI/Gradio codebase.
• Design and implement a clean, scalable architecture.
• Refactor the backend into well-organized, stable modules.
• Tighten authentication and refine project management workflows.

Skills

Python

FastAPI

Backend architecture design

Systems design

Data processing pipelines

Machine learning pipelines

Job description

Are you ready to bring order to chaos and build a robust backend from the ground up? Join a focused, agile team working alongside the CTO to revamp and restructure a cutting‑edge platform. This role is perfect for a backend engineer passionate about clean architecture, modular development, and seamless system flows.

What You'll Do:

• Audit and review an existing Python/FastAPI/Gradio codebase to understand its current state and challenges.
• Design and implement a clean, scalable architecture for:
  • Document ingestion pipelines
  • Classification and routing mechanisms
  • Retrieval‑Augmented Generation (RAG) and embedding‑based indexing
  • Backend APIs for smooth interaction and integration
• Refactor the backend into well‑organized, stable modules.
• Tighten authentication and refine project, user, and session management workflows.
• Shape and optimize a sensible database schema covering studies, articles, projects, users, and organizations.
• Collaborate closely with the CTO in a small but high‑impact team.

What We’re Looking For:

• 6+ years of solid backend and systems design experience.
• Expert‑level skills in Python and FastAPI.
• Proven experience structuring data processing or machine learning pipelines.
• Comfortable conducting codebase audits and delivering actionable architecture reports.
• Bonus points for experience with RAG, text extraction, and AI APIs like OpenAI or Anthropic.
• Preferably available full time, but a small part‑time commitment (around 1/4 time) can be considered.

About the Team:

You’ll be working in a lean setup with just the CTO and yourself as the core engineering force — a unique opportunity to have a direct impact on shaping the backend foundation of a forward‑thinking platform.

Hiring Process:

• A brief interview to get to know you.
• A live coding session to evaluate your approach to problem‑solving.