Senior Fullstack Engineer - AI

Senior Fullstack Engineer - AI LumApps is now more than just an Employee Experience Platform — it is an AI-powered Employee Hub that supports companies in their digital transformation of communication, collaboration, and engagement with their customers, partners, and above all their employees. Our platform is a proven leader in this dynamic market with a truly unique vision and product. It has been deployed by Fortune 500 clients around the world and is delivering meaningful business benefits. LumApps is identified as a leader in Gartner's Magic Quadrant for Intranet Packaged Solutions as well as in Intranets Forrester Wave, and regularly selected for the French Tech Next40/120 program. ✨ In 2025, LumApps strengthened its leadership position by partnering with Beekeeper , a pioneer in frontline employee experience solutions. This strategic collaboration expands our reach and impact across all types of workers — from HQ to the frontline. Our mission: To make people feel that they belong and have a purpose. To create an environment where all employees are engaged and work together towards the same goal. Over 700 leading companies trust our solution to: 🎯 Improve the productivity of their teams with our AI-powered Collaborative Experience Platform integrated with both Google and Microsoft collaborative suites, 🎯 Transform employees into real ambassadors of their company, 🎯 Make employees more efficient and better connected to their peers and relevant information, regardless of their location, with the tools and information they need at their fingertips, 🎯 Help companies reduce turnover, accelerate employee onboarding, better collaborate and share knowledge, and even improve their customer experiences. With a team of over 600 Lumies spread across 11 offices (Lyon, Paris, Lille, Sophia Antipolis, London, Barcelona, Hamburg, Austin, Tokyo, Zurich, Krakow), we support large enterprises all around the world. Over the past year, we have been driving an ambitious phase in our journey under the impulse of our new shareholder Bridgepoint, aimed at propelling us to become the clear leader in our market and shine worldwide in our industry. We are looking for individuals who are excited to actively participate in this transformation. If these core values sound like you: "be bold, do amazing things" , "say what you mean, do what you say" , "one team, same mission" , "always be evolving" : apply now! *Team* The AI Agents Platform Team is at the heart of LumApps' most ambitious product bets. We design, build, and evolve the systems that power AI-driven experiences across the platform —from conversational agents and agentic workflows to intelligent content tools and multi-modal AI interactions, end to end from the API to the UI. Our scope includes: Agent Chat: real-time streaming chat interfaces powered by the AG-UI protocol and Server-Sent Events. Agent Studio: the management layer for creating, discovering, and governing AI agents at scale, with the support of backend/frontend/RAG tools. Agent interoperability: connecting our agents to the broader ecosystem through the Model Context Protocol (MCP) and Agent-to-Agent (A2A) protocols, exposing and consuming tools and remote agents securely at enterprise scale. You will work primarily on our backend services — core/ask (the conversational/agent runtime) and core/mcp (our MCP gateway and tool/agent integration layer) — Python microservices built on Clean Architecture, while also contributing to the React/TypeScript surfaces that consume them. As a Senior Full Stack Software Engineer, you will play a decisive role in shaping the technical direction of the tribe. This is not just an implementation role — you will own architectural decisions, mentor engineers, drive cross-team alignment, and ensure we build AI-powered experiences that are robust, secure, and delightful to use. You will work closely with product managers, designers, frontend and backend engineers, and AI researchers, and you will have a direct impact on how tens of thousands of employees experience AI in their workplace. *Missions* Technical Leadership & Vision Define and own the technical vision for the AI Agents tribe across the stack. Drive major architectural decisions — from agent communication protocols (MCP, A2A, AG-UI) and streaming patterns to data modeling, service boundaries, and state management — while tracking implications on adjacent systems and teams. Independently scope and implement complex end-to-end solutions, from API and data layer through to the user-facing experience. Identify and proactively tackle technical debt. Cross-Team Collaboration & Delivery Plan and execute projects that span multiple teams within the tribe. Partner with product and engineering leadership to translate roadmap goals into concrete technical strategies, providing reliable project estimates and owning delivery accountability. Quality & Engineering Excellence Define canonical patterns and lead-by-example on testing, performance, observability, and security. Conduct rigorous code reviews and challenge both specifications and implementations when needed. Developer Growth & Knowledge Sharing Mentor Software Engineers, providing actionable feedback on strategy, impact, execution, and technical depth. Share knowledge through engineering articles, internal presentations. *Skills* A Senior Full Stack Engineer: You have 6+ years of professional software engineering experience, with deep expertise in Python for backend services and solid command of TypeScript and React (v17+) on the frontend. You have strong opinions on API design, service boundaries, component design, performance optimization, and maintainability at scale in a large monorepo. A Backend Architect: You are comfortable building production microservices following Clean Architecture / SOLID principles — designing clear domain layers, working with relational databases (PostgreSQL, SQLAlchemy), event-driven patterns (Pub/Sub), and REST/OpenAPI contracts. You have shipped and operated services in the cloud (GCP and/or Azure). An AI & Agent Systems Specialist: You are excited about building at the frontier of AI-powered UX. You have hands-on experience — or strong curiosity — with agent interoperability protocols like the Model Context Protocol (MCP) and Agent-to-Agent (A2A), agent-to-UI streaming via the AG-UI protocol (SSE, WebSockets), and integrating with LLM providers such as Google Gemini and Mistral running on Vertex AI, using agentic frameworks like Google ADK or Strands Agents. An Architect, Not Just a Developer: You can design systems end-to-end. You think about functional correctness, technical scalability, and security implications simultaneously. You have contributed to — or led — significant architectural decisions in a production codebase. A Quality Champion: You set the standard on testing across the stack. You are proficient with backend unit/component/integration testing (pytest and equivalents) as well as frontend tooling (Jest, React Testing Library, Storybook, Playwright). You know the difference between testing for coverage and testing for confidence. A Technical Communicator: You speak English fluently and can relay the big picture to engineers, product, and leadership alike. You challenge ambiguous specs, write clear design documents, and make complex tradeoffs legible to non-technical stakeholders. A Mentor and Culture Builder: You invest in the people around you. You give direct, constructive feedback, share knowledge proactively, and care about building a team culture grounded in psychological safety and technical excellence. A Security & Reliability Advocate: Securing access to tools, agents, and user data is not an afterthought for you. You design with authentication, authorization, and tenant isolation in mind, and you build services to be observable and resilient from the start. 💡 Why You’ll Love Working at LumApps We’re proud to offer a work environment where people feel supported, valued, and empowered. Here’s a peek at what we offer: 🏡 Hybrid work model – 2 days at the office, 3 days remote 🕒 RTT days – ~10 extra days off per year 💳 Meal vouchers (SWILE) + free snacks & coffee 🧘‍♀️ Yoga classes - Take a mindful break in our Paris office 👶 Supportive parental leave and family moments — yes, even a Christmas party for your kids ! 🛡️ Health insurance (ALAN) – 60% covered + full life & disability cover 🎉 Afterworks, team celebrations & seasonal parties 💻 Equipment of your choice 🗣️ French & English lessons , professional development & access to Leeto CSE We aim to celebrate diversity and are committed to creating an inclusive environment for all employees. We encourage applications from candidates of all backgrounds, identities, and experiences. Department Engineering EMEA Role Software Engineer, Frontend Locations Lyon, Paris, Sophia-Antipolis, Tassin-la-Demi-Lune, Bordeaux Remote status Hybrid Lyon Paris Sophia-Antipolis Tassin-la-Demi-Lune Bordeaux LumApps is... A company that has been growing for more than 10 years Nearly 400 Lumies worldwide More than 700 customers Offices in Austin, Paris, Lyon, Lille, Sophia-Antipolis, London, Tokyo, Hamburg and Barcelona Our greatest pride? Our talents come from a variety of backgrounds and are passionate about creating a unique, powerful solution that delivers the best possible employee experience. About LumApps LumApps is an Employee Experience Platform that helps organizations thrive in a digital environment by connecting and empowering employees with purpose and belonging. Founded in 2015 Co-workers 400