Senior Full Stack Engineer – AI Platform

About the role

We are hiring a Senior Full Stack Engineer to join a fast‑growing Series B AI startup building an AI operating system for enterprise customers. The role is based in Paris with a four‑day onsite cadence and full relocation support.

Key responsibilities

• Design, develop, and ship production‑grade AI agents and the supporting infrastructure (tool calling, memory, guardrails, escalation logic).
• Build end‑to‑end agent workflows that integrate deeply with enterprise data sources, internal systems, and third‑party services.
• Integrate and evaluate leading large‑language models from OpenAI, Anthropic, Gemini, Mistral, and open‑source alternatives.
• Develop and optimise retrieval‑augmented generation (RAG) pipelines, retrieval infrastructure, evaluation harnesses, and observability tooling.
• Shape new product features from concept to launch, collaborating directly with founders, product, and engineering teams.

Required profile

• 5+ years of software engineering experience with a strong track record in production AI/ML or agent systems.
• Deep full‑stack expertise, especially backend development (TypeScript, Node.js, Python, PostgreSQL or equivalent).
• Hands‑on experience shipping AI‑powered products used by customers daily.
• Background in high‑velocity startup or product‑focused environments.
• Ability to frame problems from first principles, own ambiguous scope, and deliver quickly.
• Excellent communication skills for interacting with engineers, founders, and enterprise customers.

Required skills

• TypeScript
• Node.js
• Python
• PostgreSQL
• OpenAI API
• Anthropic models
• Google Gemini
• Mistral models
• RAG pipelines
• Retrieval infrastructure
• Evaluation harnesses
• Agent observability

What we offer

• Base salary up to €130,000 per year
• Significant equity package
• Full relocation support to Paris
• Modern office in central Paris with a four‑day onsite schedule
• Direct access to founders and ownership of scope from day one
• High‑quality equipment, learning budget, and standard benefits of a top‑tier AI company