Senior FastAPI Engineer

About us

comm1t connects experienced IT professionals with companies across Poland and Europe 🇪🇺. We bring together recruitment expertise and AI-powered sourcing, focusing on opportunities that fit each candidate’s skills, priorities, and career direction.

We support both sides throughout hiring and onboarding, staying close as the collaboration gets underway.

About our client

We’re hiring for a growing technology company developing AI software for legal and professional services organizations. Its products help teams navigate large volumes of documents, find relevant information, and handle knowledge-intensive work involving sensitive data.

The company already serves paying customers and is expanding its engineering team to support further product development.

About the role

As a Senior Python / FastAPI Developer, you’ll be responsible for the backend services that turn AI capabilities into dependable product features.

You’ll connect language models with application logic and data sources, build document processing workflows, and ensure that background tasks and user-facing APIs operate reliably as usage grows. The role combines hands-on development with architectural ownership, with particular attention to performance, data protection, and the quality of AI-generated results.

Your responsibilities

• Develop and maintain APIs and backend services in Python and FastAPI

• Build workflows for document retrieval, LLM orchestration, tool execution, and response streaming

• Implement evaluation mechanisms to measure and improve AI output quality

• Design asynchronous pipelines for document ingestion, embedding generation, and time-consuming processing tasks

• Build and maintain integrations with email services and document management platforms

• Address performance bottlenecks and failure scenarios across distributed services

• Ensure secure handling of confidential information and clear separation of customer data

• Contribute to architecture decisions and engineering standards

Requirements

• 7+ years of experience developing backend systems used in production

• At least 6 years of Python experience and 3 years working with FastAPI

• Practical knowledge of PostgreSQL and SQL

• At least 2 years of experience with Redis

• A strong understanding of asynchronous processing, system reliability, and designing for failure

• Experience with LLM-based systems, or a strong motivation to work with RAG, agents, and tool-calling

• Effective use of AI development tools such as Claude Code, Cursor, or Copilot, with full responsibility for code quality

• A proactive approach to technical ownership and comfort with changing startup priorities

Tech stack

• Backend: Python, FastAPI

• Database: PostgreSQL / SQL

• Caching & background processing: Redis, Celery

• Messaging: RabbitMQ

• Cloud: Microsoft Azure

Nice to have

• Experience building RAG solutions or implementing vector search

• Familiarity with LangChain or LlamaIndex

• Knowledge of SSE, WebSocket, or SignalR

• Experience integrating Microsoft Graph or email platforms

What you can expect

• Direct influence on backend architecture and product development

• Close collaboration with a small engineering team

• Practical AI challenges involving real customers and production workloads

• A flexible, English-speaking environment

• The opportunity to help shape engineering practices as the team expands

Tech stack

• fastapi
• Python
• PostgreSQL
• Celery
• asyncio
• RabbitMQ
• Redis
• Azure
• Langchain