Lead LLM

Leonar

Paris, FRonsitePosted Jun 16, 2026
Posting intelligenceActively listedReposted 5×, possible evergreen/ghost posting

Skills

regressionlangchainpostgresposthogpythonopenaiazurellm

About the role

Licorne Society a été missionné par une startup IA en pleine croissance pour les aider à trouver leur Lead LLM Engineer.

What You Will Own

You will be responsible for one thing:

Make our AI outputs reliable, fast, and indispensable in real workflows.

Concretely

Design and evolve our LLM / agent architecture

Own output quality across key use cases (emails, document analysis, etc.)

Build evaluation systems (datasets, metrics, regression detection)

Drive fast iteration loops from production data

Improve retrieval, reasoning, and tool usage

Ensure production reliability (latency, failure modes, fallback)

Work directly with product + founders on what to build and why

What This Role Is Really About

Most teams fail because:

they don’t know what “good output” means

they don’t have evals

they iterate randomly

they overuse agents

Your job is to fix that.

You Will Turn

vague user problems

→ into structured AI systems

→ with measurable performance

→ that improve every week

What You Need To Be Excellent At

Shipping real LLM systems

You’ve built systems used in production (not demos)

You understand RAG, tools, agents, structured outputs

You can design full pipelines, not just prompts

Evaluation-driven development

You know how to define quality metrics

You build datasets from real usage

You run continuous evals to prevent regressions

Debugging complex failures

You can trace issues across:

retrieval

prompts

model behavior

You don’t guess — you isolate and fix

Speed of iteration

You move from problem → improvement in hours or days, not weeks

You use logs, traces, and data — not intuition alone

Strong judgment

You know when to:

use an agent vs a pipeline

add complexity vs simplify

You optimize for reliability and user value, not novelty

What We Don’t Care About

Number of years of experience

Whether you’ve used a specific framework

Fancy research credentials

If you can build, debug, and improve real systems, you’re a fit.

What Success Looks Like (first 90 Days)

Clear eval framework for core use cases

Measurable improvement in output quality

Faster iteration cycles across the team

Reduced hallucinations / failures

Stronger system architecture decisions

Stack (context, Not Requirements)

Python (FastAPI)

Postgres

Google Cloud

LangGraph / LangChain (evolving)

PostHog (product analytics)

Langfuse (LLM traces)

LLM APIs (Azure OpenAI)

Questions about this role

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Compensation for LLM Engineer roles in France varies widely by seniority, employer size, and remote vs onsite arrangement. Check the salary range on this listing when published, or browse our LLM Engineer hub for France medians across recent openings.

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