Senior FastAPI Engineer

About uscomm1t 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 clientWe’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 roleAs 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 responsibilitiesDevelop and maintain APIs and backend services in Python and FastAPIBuild workflows for document retrieval, LLM orchestration, tool execution, and response streamingImplement evaluation mechanisms to measure and improve AI output qualityDesign asynchronous pipelines for document ingestion, embedding generation, and time-consuming processing tasksBuild and maintain integrations with email services and document management platformsAddress performance bottlenecks and failure scenarios across distributed servicesEnsure secure handling of confidential information and clear separation of customer dataContribute to architecture decisions and engineering standardsRequirements7+ years of experience developing backend systems used in productionAt least 6 years of Python experience and 3 years working with FastAPIPractical knowledge of PostgreSQL and SQLAt least 2 years of experience with RedisA strong understanding of asynchronous processing, system reliability, and designing for failureExperience with LLM-based systems, or a strong motivation to work with RAG, agents, and tool-callingEffective use of AI development tools such as Claude Code, Cursor, or Copilot, with full responsibility for code qualityA proactive approach to technical ownership and comfort with changing startup prioritiesTech stackBackend: Python, FastAPIDatabase: PostgreSQL / SQLCaching & background processing: Redis, CeleryMessaging: RabbitMQCloud: Microsoft AzureNice to haveExperience building RAG solutions or implementing vector searchFamiliarity with LangChain or LlamaIndexKnowledge of SSE, WebSocket, or SignalRExperience integrating Microsoft Graph or email platformsWhat you can expectDirect influence on backend architecture and product developmentClose collaboration with a small engineering teamPractical AI challenges involving real customers and production workloadsA flexible, English-speaking environmentThe opportunity to help shape engineering practices as the team expands