AI Engineer, Product, (Le Chat)

Full-time

Job Description

About Mistral

At Mistral AI, we believe in the power of AI to simplify tasks, save time, and enhance learning and creativity. Our technology is designed to integrate seamlessly into daily working life.

We democratize AI through high-performance, optimized, open-source and cutting-edge models, products and solutions. Our comprehensive AI platform is designed to meet enterprise needs, whether on-premises or in cloud environments. Our offerings include le Chat, the AI assistant for life and work.

We are a dynamic, collaborative team passionate about AI and its potential to transform society.

Our diverse workforce thrives in competitive environments and is committed to driving innovation. Our teams are distributed between France, USA, UK, Germany and Singapore. We are creative, low-ego and team-spirited.

Join us to be part of a pioneering company shaping the future of AI. Together, we can make a meaningful impact. See more about our culture on https://mistral.ai/careers.

Role summary

Embedded directly in Le Chat product Team, you will build the evaluation and A/B testing framework, add end-to-end observability, and run a reliable model release process. Work with Science to ship measurable improvements to quality, latency, safety, and reliability

What you will do

• Build and maintain an LLM evaluation framework (reference tests, heuristics, model-graded checks).

• Define and track metrics: task success, helpfulness, hallucination proxies, safety flags, latency/cost.

• Run A/B tests for prompts, models, and system prompts, analyze results, recommend rollout or rollback.

• Set up observability for LLM calls: structured logging, tracing, dashboards, alerts.

• Operate the model release: canary and shadow traffic, sign-offs, SLO-based rollback criteria, regression detection.

• Improve core behaviors: memory write/retrieve policies and evals, intent classification, follow-ups, routing, tool-call reliability.

• Create templates and docs so other teams can author evals and ship safely.

• Partner with Science, diagnose regressions and lead post-mortems.

About you

• Strong TypeScript or Python skills

• Production LLM experience: prompts, tool/function calling, and system prompts.

• Hands-on with evals and A/B testing, you can design metrics and make rollout decisions from data.

• Observability: logging, tracing, dashboards, alerting

• Product mindset: form hypotheses, run experiments, interpret results, iterate.

• Clear written and spoken communication, autonomous; and product-oriented.

Now it would be ideal if you have experience with

• Safety systems: moderation, PII handling/redaction, guardrails.

• Release operations: canary/shadowing, automated rollbacks, experiment platforms.

Hiring Process

• Introduction call - 45 min

• Hiring Manager interview - 30 min

• Technical Rounds

- Live-coding Interview (Machine Learning) - 45 min

- Live-coding Interview (Algorithm) - 45 min

• Culture-fit discussion - 30 min

• References

Location & Remote

This role is primarily based at our HQ in Paris, France. We will prioritize candidates who either reside in Paris or are open to relocating. We strongly believe in the value of in-person collaboration to foster strong relationships and seamless communication within our team. Our remote work policy is designed to offer flexibility, enhance work-life balance, and boost productivity. The number of remote workdays is determined by each manager, taking into account individual autonomy and specific circumstances—such as increased flexibility during the summer months. Regardless of the arrangement, we expect all employees to maintain open lines of communication with their teams and be available during core working hours.

In certain specific situations, we will also consider remote candidates based in one of the countries listed in this job posting (currently France, UK, Germany, Netherlands, Spain and Italy). In that case, we ask all new hires to visit our Paris office:

• for the first month of their onboarding (accommodation and travelling covered)

• then at least 3 days per month

What we offer

💰 Competitive salary and equity

🧑‍⚕️ Health insurance

🚴 Transportation allowance

🥎 Sport allowance

🥕 Meal vouchers

💰 Private pension plan

🍼 Parental : Generous parental leave policy

🌎 Visa sponsorship

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