Founding Fullstack Engineer Rose

Hexa; Paris; Hybride; EUR 60 000 - 80 000; Plein temps

Résumé du poste

A leading startup studio in Paris is seeking a Founding Engineer to develop the Rose platform alongside the CTO. This role focuses on cutting-edge technical challenges including AI implementation and product integrations. Candidates should have significant full-stack development experience, particularly in React and Python. The position offers a competitive salary, a MacBook Pro, premium health insurance, and a hybrid work model.

Prestations

Competitive salary

Latest MacBook Pro

Premium health insurance

Hybrid remote work model

Qualifications

• 4 years of experience in full-stack development on B2B SaaS products.
• Experience with REST or GraphQL API design.
• Ability to work on technical architecture with minimal supervision.

Responsabilités

• Co-build the technical architecture with the CTO.
• Develop core features like conversational AI engine.
• Participate in product decisions and user exchanges.

Connaissances

Full-stack development experience

Frontend mastery in React/TypeScript

Backend development experience in Python

Experience with SQL and NoSQL databases

Ability to define technical architectures

Experience deploying applications in production

Outils

Python

FastAPI

PostgreSQL

MongoDB

React

TypeScript

GCP

Description du poste

Overview

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. Rose is part of a portfolio with a multi-billion dollar ambition and a track record of funding and growth. Rose aims to transform B2B websites into intelligent conversational assistants to engage traffic, capture zero-party data, and increase demo conversions. Our clients include Pennylane, Mayday, and Tasty in production.

The role of the Founding Engineer is to build the Rose platform alongside the CTO / Cofounder, with immediate impact on product and users.

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 in 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, FastAPI, 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 full-stack 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
• Latest MacBook Pro
• Premium health insurance (Alan or equivalent)
• Joining a renowned startup studio: a dynamic environment with smart and ambitious people
• 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 and discussion about your background
• CTO interview (45 min) — Discussion about your experiences and technical approaches
• Tech assessment (2-3 hours max) — Realistic technical problem related to our challenges (remote possible)
• Final meeting (2 hours) at the office — Technical deep dive and culture fit with JoHary, CEO & Florent, Partner Hexa
• References and formal offer

Key Skills

ASP.NET, Health, Education, Fashion Designing, Fiber, Investigation

Employment Type : Full-Time

Experience : years

Vacancy : 1