Senior Fullstack Developer (PHP + Python + Vue/React) – AI Agents

Description

Job Summary: We are looking for a Senior Fullstack Engineer to build the next generation of our HR platform using multi-agent systems and lead the evolution of our applied AI platform. Key Highlights: 1. Build and deploy autonomous agents in production. 2. Lead the evolution of our applied AI platform. 3. Work with cutting-edge technology and real systems in production. Hello! At Sesame, we are building the next generation of our HR platform using multi\-agent systems that automate real processes in production — not prototypes, not demos, not notebooks. We seek a Senior Fullstack Engineer with solid experience in Symfony (or Laravel with willingness to migrate), Python with FastAPI, and Vue 3 / React on the frontend, who has built and deployed autonomous agents in production and wants to lead the evolution of our applied AI platform. If you’ve been doing fullstack development for years and, over the past 1\-2 years, have transitioned into building agentic AI applications with LLMs — orchestration, RAG, tool use, memory, evaluations — this role is for you. Our Tech Stack * Backend: Symfony (PHP), Python (FastAPI), Node.js * Frontend: Vue 3, React * AI / ML: LangChain, LangGraph, Mastra, OpenAI, Anthropic * Infra: AWS, Docker, PostgreSQL, Redis * Data: pgvector, embeddings, RAG pipelines What We Expect From You? **Technically, you must have:** * 5+ years of software development experience, with a focus on complex production systems. * Solid experience developing AI applications beyond prototypes or research. * Experience designing, building, and deploying autonomous agents in production. * Experience with multi\-agent orchestration, state management, memory, and autonomous decision-making. * Practical knowledge of tool use, function calling, and integrating agents with APIs and external systems. * Experience implementing RAG pipelines and working with vector databases (Pinecone, Chroma, pgvector…). * Integration experience with LLM APIs such as OpenAI, Anthropic, or open-source models. * Ability to design scalable and reliable architectures for production AI systems. * Experience working with Docker and cloud deployments (AWS, GCP, or Azure). * A practical mindset: here, we build real products, not academic research. * Ability to understand business problems and translate them into effective technical solutions. * Adaptability to change (yes, we’re a startup). * Constant curiosity and desire to improve both the product and existing code. **✨ Bonus points if you also have:** * Strong experience with Python for AI application development. * Proficiency in Symfony (PHP) for backend development. * Experience with Vue 3 and/or React on the frontend. * Experience designing evaluation frameworks to measure agent reliability and quality. * Familiarity with techniques such as reflection, self\-correction, and response verification in agents. * Comfort working with distributed systems and modern architectures. ‍ ‍ What Will You Do at Sesame? * Design and develop end\-to\-end agentic applications for HR process automation. * Build multi\-agent systems with orchestration, memory, and autonomous decision-making. * Implement RAG pipelines to provide business context to agents. * Create guardrails and human\-in\-the\-loop workflows to ensure reliability and compliance. * Maintain and evolve our backend in Symfony, Python, and Node.js, and frontends in Vue 3 / React. * Define scalable architectures for production AI systems. * Collaborate closely with product to transform business needs into real agentic solutions. How Will You Grow Within the Company? * In your first weeks, you’ll deeply learn the product, team, and our applied AI approach, with technical onboarding and mentoring. * In your first months, you’ll develop and evolve key agentic features, working hand-in-hand with our AI and product teams. * As you gain context, you’ll begin defining architecture, proposing improvements, and leading technical decisions. * Once fully onboarded, you’ll play a key role in evolving our AI platform, directly influencing the roadmap and technical strategy. ✈️ Every feature is a new adventure You’ll work with cutting-edge technology, real systems in production, and a team highly motivated to do things right. Are you up for the challenge?