About the role

As our Python Product Developer, you will be at the forefront of building the next generation of AI systems—combining large language models with formal verification methods to create hallucination-free, transparent, and cost-efficient solutions.

This is a hands-on technical role where you'll design and implement core machine learning algorithms, develop product features based on customer feedback, and bridge Python with high-performance compiled languages. You'll work directly with the founding team to shape the product roadmap and translate cutting-edge research into production-ready systems.

You'll be joining a founding team of deep-tech experts at a critical inflection point—moving from research breakthroughs to real-world deployment with design partners in high-stakes domains where AI reliability is paramount.

Key responsibilities

• Develop product features: Build and ship production-grade features for our platform, working across the full stack from backend APIs to UI prototypes using Python
• Collaborate with design partners: Work closely with 2-3 early customers to gather requirements and feedback, translating their needs into technical specifications and contributing to the product roadmap
• Build Python-native bridges: Design and implement high-performance integrations between Python and compiled languages (Rust, Go, C++)
• Build reusable infrastructure: Create documentation, code templates, and engineering best practices that enable the team to scale our development approach as we grow
• Bridge research and practice: Work closely with the founding team, including research scientists, to translate cutting-edge formal methods research into production-ready Python implementations
• Design ML algorithms (long term): Design, prototype, and optimize machine learning algorithms that power our formal verification capabilities, including graph processing, anomaly detection, and optimization techniques

What we are looking for

Essential qualities

• Python mastery: You speak Python as a second language and literally dream in OOP—you understand object-oriented design patterns deeply and write clean, maintainable code
• Product mindset: You're passionate about building features that match user needs and can respond to customer feedback with elegant technical solutions
• Polyglot expertise: You have deep knowledge of bridging Python with high-performance compiled languages and understand the trade-offs involved
• A relentless drive for applicability: You prioritize real-world impact, the continuous integration of field feedback

Background

• 5+ years of hands-on Python development experience with proven ability to build production systems
• Experience building machine learning or data-intensive applications
• Track record of working across multiple programming languages and integrating different technology stacks

Required skills

• Python full-stack mastery: Proficiency in Python-based backend frameworks (FastAPI, Flask, Django, etc.), solid foundations in databases (SQL, NoSQL), and core skills in cloud computing and server management (any Cloud CLI, Bash, Docker, etc.)
• UI prototyping: Hands-on experience with a framework like Streamlit, Gradio, Dash, or similar
• JavaScript fundamentals: Fundamental knowledge of JavaScript for frontend integration
• Polyglot programming: Expertise in at least one other programming language such as C++, Rust, Go, etc
• Native bridges: Proven expertise in bridging Python with compiled languages (developing Python bindings, FFI, ctypes, cffi, pybind11, or similar)
• ML skills (optional): Demonstrated experience or strong interest in graph processing, anomaly detection, optimization algorithms, and complex data visualization

Benefits

• Financial & perks
  • Competitive cash salary and equity (BSPCE) in a high-potential company.
  • Health insurance (Alan) for you and your family (partner and kids).
  • Daily lunch vouchers (Swile).
  • Hybrid work model with a strong emphasis on in-office collaboration (typically 3-4 days per week at the office) to foster team cohesion, spontaneous discussions, and deep work together.
• What makes this role unique:
  • Founding team impact: Join as one of the first employees and shape the trajectory of a moonshot deep-tech company.
  • Mission-driven startup: Help solve the key pressing challenges of AI—the most transformative technology of our era—ensuring LLMs are trustworthy, transparent, and cost-effective, with direct benefits for environmental sustainability.
  • Work with cutting-edge technology: Build systems that combine LLMs with formal verification—an emerging field at the forefront of AI safety and reliability where breakthrough developments happen every week.
  • World-class team: Collaborate with a scientific advisory board from leading institutions (Ecole polytechnique, ENS Paris-Saclay, etc) and experienced business angels from top tech companies (Datadog, Dataiku, Nabla, Artefact, and more).
  • Strategic customers: Work with leading companies in healthcare, enterprise software, and other mission-critical domains.
  • Flexibility of an early-stage startup: Autonomy to define how you work and what you prioritize.

Hiring process

1. Apply and submit your resume using this Google Form
2. Screening call (30 min): A quick chat with the CTO to align on vision and expectations.
3. In-depth technical discussion (home exercise followed by a 60 min discussion): Best way to decide if we are a great fit as potential collaborators.
4. Technical deep-dive (60 min): A focus on your proficiency with the tools you will use.
5. Founder interview (45 min): Final discussion on strategy, culture fit, and your long-term evolution within the company, with the CTO and CEO.