Founding AI Engineer @Plato (backed by Hexa) Hexa
Startup studio launching companies in AI, fintech, health, and web3.
Permanent
Paris
Occasional remote
Salary: Not specified
> 2 years
Skills we're looking for
Problem-solving skills
Aircall
React
Pydantic
TypeScript
+5
You'll be part of
Incubateur / Accélérateur
Accompagnement d'entreprises
Average age: 34
60%
40%
Founded in 2011 as eFounders, Hexa is a startup studio that has launched over 40 companies with a combined valuation of over $4.5bn, including Aircall, Spendesk, Front, Swan, Yousign, and Upflow.
Today, our focus is on launching companies in the areas of AI, future of work, health, fintech, and web3 - with even more verticals to come. By 2030, our goal is to launch 30 startups a year.
Our unique model allows us to build companies from scratch in collaboration with exceptional founders, bringing them on board for 12 months while building the company together, from product to fundraising.
How do we do it? We provide entrepreneurs with:
- Foolproof startup ideas to beat the odds
- A team to build a best-in-class MVP
- A methodology to bring their product to market faster
- A brand to attract top talents
- Capital to fund the first 12-18 months of their startup’s life
- A community of fellow entrepreneurs & peers for life
Our approach creates exceptional companies: for us, that means startups that are fueled by ambition, and driven by purpose.
You'll be working on
Plato is building the AI OS for litigation lawyers.
With AI, the legal industry is on the verge of a major transformation. Litigation lawyers are overwhelmed by complex and repetitive tasks: complex damage calculations, thousands of documents to review, days spent drafting legal documents, and more.
Our mission: Build the leading AI OS for litigation lawyers, enabling professionals to work 5x faster, by putting their whole firm on autopilot.
Plato already supports more than 30 law firms and 1 major insurance company’s legal team, who use our solution daily to manage hundreds of active cases.
Founded in January 2026 by Ben (CEO) and Alexandre (CTO), we are backed by Hexa (formerly eFounders), Europe’s leading startup studio. Hexa has launched over 35 companies, including unicorns such as Front, Aircall, and Spendesk, collectively generating more than €230M in ARR and raising over €750M in funding.
Plato is live with real users, real data and real revenue, solving concrete legal workflows in production. We’re now looking for a Founding AI Engineer to help us turn the latest advances in AI into reliable products used every day by legal professionals.
🎯 Your mission
You’ll work directly with Alexandre , our CTO, at the intersection of AI, software engineering and product.
Your job is not to do AI research for the sake of research. You’ll experiment with models and approaches, understand what works, and turn the best solutions into reliable production systems.
You’ll work on problems such as building agentic workflows, making sense complex legal documents, designing autonomous long-running agents, and improving the quality and reliability of AI-generated outputs.
Responsibilities
Build AI-powered product features
Design and ship AI features used directly by lawyers
Be at the bleeing edge of the agentic stack: memory, sandboxes, code mode, lots of tools, subagents…
Turn prototypes and experiments into production-ready feature
Work with complex data
Extract, structure and reason over large volumes of unstructured legal documents
Build robust data and document-processing pipelines
Experiment with different models and approaches to improve accuracy and reliability
Make AI work in production
Evaluate and improve agent outcomes through testing, evals and iteration
Optimize systems for quality, latency and cost
Build the backend services and infrastructure needed to run AI reliably at scale
Shape the product
Work directly with the founders and users to understand real-world problems
Move quickly from problem → experiment → production (think days, not weeks)
Take ownership of your projects from exploration to deployment
We're looking for
We’re looking for a strong software or AI engineer with 2+ years of experience who wants to build real-world AI products at the forefront of the agentic stack.
You like working close to founders and users, making pragmatic technical decisions, and shipping software that actually runs in production.
You’ll thrive in this role if you:
Have a strong software engineering foundation, ideally with Typescript and experience shipping production systems
Have experience with agents and/or evals and frameworks like Mastra, Eve, Pydantic, Langchain, etc…
Can take an AI problem from experimentation to production
Enjoy solving problems with no clear solution
Have a strong product mindset and care about user impact
Are autonomous and pragmatic, comfortable navigating early-stage ambiguity and shipping fast
⚙️ Our tech stack
Our stack is designed to support AI-first workflows and production reliability.
Backend & Frontend: TypeScript, Node.js, React, tRPC
Infrastructure: AWS (Terraform)
Data & AI: Mastra, Bedrock
Database: Postgres
You don’t need to master every tool — what matters is your ability to design robust systems, learn fast, and make sound technical trade-offs.
💎 What we offer
Build alongside a strong AI expert: Work closely with Alexandre, our CTO, who has deep expertise in AI agents, and turn cutting-edge AI into production systems.
Ownership & Impact: As the second engineering hire, you’ll have real influence on the product and technical direction
Bring AI to real users: Build production AI systems that solve real problems in a complex, high-stakes domain
Hexa ecosystem: Access to expertise, resources, and network from one of Europe’s leading startup studios
Competitive package: Attractive salary + meaningful equity
Paris-based team: Work alongside the founding team in our office
Growth: Opportunity to grow into a technical leadership role as the team scales
Plato is committed to creating a diverse environment. All qualified applicants will receive consideration for employment irrespective of gender, origin, identity, background and sexual orientation.
We know there’s a long way to go regarding diversity in our industry, which is why we encourage all applicants to apply to our open positions.
Key figures
In short
Average age
34
Gender
40%
60%
