Retour aux Emplois

Founding Fullstack Engineer @Rose

Paris
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 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, 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.

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
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, CEO & Florent, Partner Hexa

- References and formal offer
Publié le 2026-02-15

Emplois Recommandés

Médecin rééducateur MPR H/F - CDD Bobigny

Agence Samovar
Paris

CDD pouvant évoluer vers un CDI de Médecin MPR à Bobigny. Structure de rééducation fonctionnelle moderne située en région parisienne, notre centre accueille des patients adultes atteints de trouble…

Voir les Détails
Publié le 2025-12-24

Data Analyst senior - Freelance

Collective.work
Paris

Taux journalier (TJM): 600 Le Contexte du Projet Dans le cadre de la transformation de ses outils de pilotage, notre Groupe spécialisé dans l’assurance-vie et l’épargne souhaite centraliser et autom…

Voir les Détails
Publié le 2026-02-12

Chargé.e RH (stage)

Pix
Paris

Qui sommes-nous Chez Pix, nous travaillons pour permettre à chaque citoyen de mesurer, d'améliorer et de valoriser tout au long de sa vie son niveau de maîtrise des usages numériques. Comment ?…

Voir les Détails
Publié le 2026-02-10

Azure devops et dev python - Freelance

Collective.work
Paris

Taux journalier (TJM): 530 Description du besoin : Client : AXA GIE Poste : Devops Azure et Python (H/F) TJM d’achat max : 530 Localisation : Paris 8 Mission longue : 3 ans Anglais profe…

Voir les Détails
Publié le 2026-02-12

Assistant Administratif H/F

Max Piccinini
Paris

Max Piccinini est le leader incontournable dans le domaine de la formation et du coaching pour chefs d'entreprises. À travers ses programmes, séminaires et accompagnements stratégiques, Max et son…

Voir les Détails
Publié le 2025-11-25

Expert technique métrologie / performance F/H

CENTRE DE LA FORMATION ET DU DÉVELOPPEMENT DES COMPÉTENCES
Paris

Expert technique métrologie / performance F/H 2026-19843 Au sein de l'équipe Métrologie Performance du pôle Opérations, vous participerez activement aux tests de performance des applications du SI de …

Voir les Détails
Publié le 2026-01-10

Chef-fe de Programme Calculateur Data Computers F/H

Paris

Description du poste Intitulé du poste Chef-fe de Programme Calculateur Data Computers F/H Type contrat CDI Statut (CSP) Ingénieur & Cadre Temps de travail Temps complet Par…

Voir les Détails
Publié le 2026-02-15

Chef de mission international - Le poste qui fait vraiment passer un cap

Goldman search
Paris 16e

Vous voulez jouer à un autre niveau. International, responsabilités, moyens sans renoncer à l'humain. Vous avez au moins 4 ans d'expérience en cabinet. Vous êtes à l'aise techniquement, vous ai…

Voir les Détails
Publié le 2026-01-24

Software QA Engineer (ML & Hardware)

Paris

Meet Arago and the Aragonians Arago is an AI and computer hardware company whose mission is to drive the course of history forward. We do so by accelerating breakthroughs at the intersection of AI…

Voir les Détails
Publié le 2026-02-15

Technicien Multi Technique Itinérant (m/f/d)

Apleona France SAS
Paris

Apleona recherche aujourd'hui un(e) Technicien(ne) Multi Technique Itinérant pour rejoindre nos équipes. Au sein du Pôle Technique, le/la Technicien(ne) est responsable de la maintenance, de la ré…

Voir les Détails
Publié le 2025-12-24