Leyton CognitX, the AI & Technology consulting arm of Leyton Group, is expanding its team of 200+ AI & Tech experts into Spain. We are looking for a Lead AI Engineer to provide technical leadership on AI missions for major international accounts, from prototype to production, at the head of a multidisciplinary team.

What you will do

- Lead AI missions technically: architecture, roadmap, estimates and delivery from prototype to production
- Lead and mentor the team
- Act as the senior client counterpart on technical decisions and trade-offs
- Contribute to pre-sales
- Design and oversee solutions based on RAG pipelines, LLM agents and model integration (OpenAI, Anthropic, open-source)
- Ensure quality through code reviews with SOLID, design patterns and clean code, plus unit and integration tests and TDD
- Ensure reliable deployments through CI/CD (Git flow, PR reviews)

What we are looking for

- 7+ years of experience, including 2+ years leading a team or workstream
- Experience running LLM systems in production at scale: evaluation, observability, cost and latency control, and resilient architectures (async processing, queues, caching, multi-provider fallback); event-driven experience (Kafka, RabbitMQ) is a plus.
- Expert in software engineering, LLM & GenAI (LLM APIs, prompt engineering, RAG, agents, evaluation), backend, APIs & data (REST, GraphQL,



gRPC, SQL and NoSQL, pipelines, search) and architecture, leadership & client delivery (system design, mentoring)
- Advanced in DevOps & cloud (CI/CD, Docker, Kubernetes, AWS / Azure, monitoring)
- Master’s degree or engineering school in Computer Science, Mathematics or Data Science, or equivalent
- Fluent English (client interactions and code reviews)
- Location: Sant Cugat del Vallés

Tech stack (tech agnostic: no stack is a deal-breaker)

Python, TypeScript / Node.js, Java / Spring, FastAPI, React, Angular, Next.js · LangChain, LangGraph, RAG (chunking, embeddings, vector stores), FAISS, Elasticsearch, PyTorch, TensorFlow, Hugging Face · PostgreSQL, Redis, MongoDB, Django, Kafka / RabbitMQ, GraphQL, gRPC, Docker, Kubernetes, Jenkins, Terraform, Ansible, GitHub Actions, AWS / Azure

What we offer

- Technical leadership of high-value missions with major international clients
- Autonomy and a voice in architecture, roadmap and pre-sales decisions
- A dynamic, collaborative environment that encourages innovation and experimentation
- Growth and greater responsibility within an international organization
- A high-performance culture: regular feedback, continuous improvement and a focus on delivering tangible value

📌 Lead AI Engineer (San Cugat del Vallés)
🏢 Leyton CognitX
📍 San Cugat del Vallés