Senior Backend Engineer (FastAPI)

About the role

You'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 handling lengthy background jobs without system failure. The real difficulty is making AI systems fast and reliable on confidential data at production scale, and you will own the early architecture decisions.

What you'll do

• Architect and ship the APIs and services that everything else depends on
• Own the AI plumbing end to end: retrieval, orchestration, tool-calling, streaming, and evaluation of results
• Build robust async and distributed workloads, including document ingestion, embeddings, and long-running jobs on Redis
• Integrate with client systems such as email and document stores and harden them for real-world traffic
• Ensure strong data security and isolation for confidential client materials

Who you are

• 7+ years delivering production backends
• Strong focus on failure modes and system reliability
• Experience shipping LLM systems (RAG, tool-calling, agents)
• Experience using AI coding tools (Claude Code, Cursor, Copilot) responsibly and effectively
• Comfortable working in a fast-changing startup environment

Tech stack experience

• Python: 6+ years
• FastAPI: 3+ years
• PostgreSQL / SQL
• Redis: 2+ years

Nice to have

• RAG or vector search experience
• LangChain or LlamaIndex