Senior Backend Engineer

About uscomm1t is a specialist IT recruitment agency delivering top engineers across Poland and Europe 🇪🇺. We combine experienced recruiters with autonomous AI agents and an obsessive focus on quality — sourcing 24/7 across LinkedIn, GitHub, and beyond to reach engineers who aren't actively job hunting but are open to the right move. We don't flood you with CVs. We get to know each candidate's skills, values, and goals, then send only the best-matched people — and we stay close through onboarding and the first months to make sure the placement lasts. About the roleYou'll lead the backend that drives the AI features — the APIs, the data pipelines, and the orchestration that connects the product to the language models doing the actual work. In practice that's querying across large document sets, getting trustworthy answers out of LLMs and their tool calls, pushing results to the UI as they stream, and grinding through lengthy background jobs without the whole thing toppling over. Forget CRUD. The real difficulty is making AI systems fast and reliable on confidential data, at production scale. The architecture choices land on you early, and you'll be the one living with them. What you'll doArchitect and ship the APIs and services that everything else depends onOwn the AI plumbing end to end: retrieval, orchestration, tool-calling, streaming, and the evals that tell you whether the results are worth anythingMake async and distributed workloads rock-solid — document ingestion, embeddings, and long jobs running on RedisWire up integrations with what clients already use (email, document stores) and harden them for real-world trafficPut data security and isolation front and center, because clients are handing over material they can't afford to leakWho you areSeven years or more delivering production backends — though how deep you go matters more to us than the figure itselfYou think in failure modes, not just the happy pathYou've shipped genuine LLM systems (RAG, tool-calling, agents), or you can't wait to — and you've got a feel for where they fall apartYou lean on AI coding tools (Claude Code, Cursor, Copilot) and get real value from them: more speed, yes, but you grasp and back every line — code you'd reject in someone else's review is code you won't merge in your ownA startup that keeps changing course doesn't faze you — plans get set, then torn up and redrawnTech stack experiencePython: 6+ yearsFastAPI: 3+ yearsPostgreSQL / SQLRedis: 2+ yearsNice to haveRAG or vector search experienceLangChain or LlamaIndex