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.
Your main mission will be: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)
1st call with Victoire our TAM & Ahmed our AI Engineer
Live technical interview with Ahmed & Eliott - Lead data
Interview with Charles, CEO
Reference Check & Offer
Skills Required
- 4+ years in a Data Science or AI Engineering role
- Advanced Python and SQL skills
- Strong hands-on experience with LLM-based systems
- Proficiency with agent-based frameworks (LangChain)
- Experience with deep learning libraries (PyTorch, Transformers)
- Experience deploying models on cloud infrastructure (GCP)
- Familiarity with CI/CD tools (Docker, Jenkins)
- Fluent in French and English
What We Do
lemlist is your go-to tool for business growth, trusted by over 37,000 businesses in more than 100 countries. The multi-channel prospecting platform allows you to discover your next buyers from a B2B database of 450M+ contacts, obtain their verified emails, and create effective campaigns with AI. All-in-one solution, no need for 3rd party tools, technical skills or extensive outreach experience.
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