🚀 Hexa Rose is a startup launched by Hexa, the Paris-based startup studio founded in 2011 that has created over 40 companies including Front, Aircall, Spendesk, and Swan (3 unicorns, +$700M raised, portfolio valuation >$5B). With €29M in funding finalized in 2025 and the goal to launch 30 startups per year by 2030, Hexa offers a unique environment: shared resources, expert network, and an ecosystem of hundreds of engineers and founders. 🎯 Rose in a nutshell The problem: 85% of B2B website visitors leave without interaction. Meanwhile, they use ChatGPT and Perplexity to compare solutions before even contacting you. Our mission: Transform B2B websites into intelligent conversational assistants that engage 100% of traffic, capture quality zero-party data, and increase demo conversions. Our approach: Unlike traditional chatbots (~5% engagement), Rose [https://userose.ai/] achieves 20%+ engagement through an integrated assistant experience, not an intrusive popup. Our clients: Pennylane, Mayday, AB Tasty are already using Rose in production. 💼 The role You'll join Rose as the first Founding Engineer to build the platform alongside, Benoit [https://www.linkedin.com/in/pothier/], CTO/Cofounder. You'll work on cutting-edge technical challenges in an environment where every line of code has a direct impact on the product and users. \n Your missions * Architecture & Development Co-build the technical architecture with the CTO (backend, frontend, infrastructure) Develop core features: conversational AI engine, interactive experiences, third-party integrations, back-office Make technical choices that structure the platform for the next 5 years * AI & Performance Participate to the implementation of RAG (Retrieval-Augmented Generation) systems in production with Vector database and knowledge graph Optimize real-time performance Develop guardrails and testing mechanisms to ensure AI response quality * Integrations & Product Build bidirectional integrations with CRMs (Salesforce, HubSpot) Orchestrate calendar systems (Calendly, Chili Piper) and analytics (Posthog) Participate in product decisions and user exchanges Tech Stack * Backend: Python, Fast API, PostgreSQL, MongoDB Vector Database, Neo4j * Frontend: React, TypeScript AI/ML: LLMs, Vector embeddings, prompt engineering, Langgraph * Infrastructure: GCP, GitHub Actions, monitoring and observability Tech Philosophy * We favor pragmatism over theoretical perfection, iteration velocity over over-engineered architectures, and user impact over technical elegance. You'll work in an environment where we ship quickly, test with real users every week, and learn constantly. 👤 Who we're looking for * 4+ years of experience in fullstack development on B2B SaaS products * Mastery of React/TypeScript on the frontend and a modern backend framework * Experience with Python * Experience with SQL and NoSQL databases, REST or GraphQL API design * Ability to define technical architectures and challenge design decisions * Experience deploying and monitoring applications in production Mindset * Builder first: you prefer building and iterating rather than debating for hours * Product-minded: you think about user impact before technical elegance * Ownership: you make decisions, own the results, and adjust * Adaptability: you're comfortable with ambiguity and pivots of an early-stage startup * Technical curiosity: you love learning (generative AI, for example, even if you're a beginner) Nice to have * UX and design sensibility * Experience with complex third-party integrations (CRM, analytics, calendars) * Experience with generative AI or LLMs * International or multilingual context 🎁 What we offer * Competitive salary aligned with the senior engineer market in Paris * Lastest Macbook Pro * Premium health insurance (Alan or equivalent) * Joining a renowned startup studio: you’ll be in a dynamic environment, surrounded by smart and ambitious people in a fun atmosphere * Lovely offices at Hexa, in Paris (75010) * Hybrid remote: 2 days a week in the office, the rest is up to you \n Recruitment process We respect your time with an efficient ~3 week process: - Discovery HR interview (30 min) - Rose presentation, discussion about your background - CTO interview (45min) with the CTO - Discussion about your experiences, technical approaches - Tech assessment (2-3h max) - Realistic technical problem related to our challenges (remote possible) - Final meeting (2h) at the office - Technical deep dive, culture fit with Johary [https://www.linkedin.com/in/johary-randriamandranto/], CEO & Florent [https://www.linkedin.com/in/florentquinti/], Partner Hexa - References and formal offer