Data Scientist / AI Engineer

lemlist is the AI-powered sales engagement platform helping sales teams build pipeline smarter, not harder.

Bootstrapped from day one, we’ve grown from 0 to $50M+ ARR in 8 years without raising a single dollar. Today, 40,000+ sales teams use lemlist to book more meetings and close more deals.

We’re building the next generation of outbound: AI-first, multi-channel, highly personalized, and deeply integrated into the way modern sales teams work.

And we’re just getting started.

We’re looking for a Data Scientist / AI Engineer to join our team. You'll be responsible for identifying and shipping AI use cases that have a direct impact on the product and the business, working closely with Product and Engineering teams.

• Identify where AI can create leverage across the product, propose concrete use cases, and take ownership from problem framing to production.

• Design, develop, and maintain LLM-based systems: prompt engineering, orchestration, retrieval pipelines, evaluation frameworks, observability…

• Deploy and operate AI models and infrastructure, including GPU server management and model serving.

• Design, train, evaluate, and maintain Machine Learning models in production.

• Support business and product teams with data-driven insights.

Within 3 months, you will have/be:

• Successfully onboarded and integrated into the team.

• Have a clear understanding of the product, data, and existing AI systems.

• Audited existing LLM systems and ML models, identified quick wins and gaps.

• Shipped a first AI use case end-to-end in production.

• Set up or improved evaluation frameworks for at least one existing LLM system.

Within 12 months, you will have:

• Shipped several meaningful AI use cases that have a measurable impact on the product.

• Built a solid evaluation and observability layer across multiple LLM systems in production.

• Improved significantly the AI culture within lemlist.

• Supported the C-level (CEO, CPO, CMO, Head of Sales…) for strategic decisions.

• Work in a profitable, bootstrapped, and high-growth company that doesn’t rely on external funding to live.

• Work on high-impact projects with highly skilled data profiles composed of a Senior Analytics Eng, a Senior Data Engineer and a Data Analyst that directly drive business decisions

• Collaborate directly with the C-suite on strategic topics

• Work with a team obsessed with speed, growth, and impact.

Must have:

• 4+ years in a Data Science or AI Engineering role, ideally in a fast-moving environment.

• Advanced Python and SQL skills.

• Strong hands-on experience building and operating LLM-based systems: model APIs, agentic pipelines, RAGs, evaluation, and observability.

• Proficiency with agent-based frameworks such as LangChain.

• Hands-on experience with deep learning libraries (PyTorch, Transformers) and embeddings (SentenceTransformers).

• Experience deploying and managing models on cloud infrastructure (ideally GCP suite).

• Familiarity with CI/CD tools (Docker, Jenkins or equivalent).

• Strong interest in getting things into production.

• Strong analytical and problem-solving mindset.

• Fast learner, high ownership, structure, and execution speed.

• Fluent in French and English.

• Paris based (Paris office / remote).

Nice to have:

• Experience with workflow orchestration tools (Airflow or equivalent).

• Experience managing GPU servers for model training and serving.

• You have a first experience in B2B SaaS startup

• Knowledge of general IT good practices - maintainable and commented code, GitHub…

• Competitive salary and company bonus (up to 18K€ per year depending on company’s performance)

• 38 days of holidays/year

• Alan Blue: Comprehensive 100% premium medical coverage for you and your family

• Swile Meal Tickets: Enjoy daily meal tickets to fuel productivity

• Navigo Card: Seamless commuting with a 100% covered Navigo card

• Gear: Get the laptop, tools, and equipment you need for your job

• Team building: We all meet once per year at really cool places around the world (check our video here)

1. 1st call with Victoire our TAM & Ahmed our AI Engineer

2. Live technical interview with Ahmed & Eliott - Lead data

3. Interview with Charles, CEO

4. Reference Check & Offer