Senior FastAPI Developer
First seen by Alion on Oct 5, 2026.
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
- fastapi
- Python
- Celery
- RabbitMQ
- Redis
- PostgreSQL