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 an AI Engineer to join a multidisciplinary team (engineers, data scientists and consultants) on high-value projects for major international clients. You will build production-grade AI: end-to-end features, RAG pipelines and LLM agents, with clean and tested code. What you will do
• Deliver end-to-end features and AI components (RAG, LLM agents, AI front-ends) with senior guidance
• Work across the full stack: front end (React, Angular, Next.js) and back end (Python, Node.js, Java / Spring)
• Develop APIs, business logic and tests, and deploy through CI/CD (Git flow, PR reviews)
• Integrate models (OpenAI, Anthropic, open-source)
• Take part in code reviews applying SOLID, design patterns and clean code
• Present technical results clearly and work in agile teams What we are looking for
• 2–4 years of experience
• Strong fundamentals: algorithms, SOLID, testing
• At least one first GenAI / LLM project shipped to production
• Proficient in software engineering, LLM & GenAI (LLM APIs, prompt engineering, RAG, agents, evaluation) and backend, APIs & data (REST, GraphQL, gRPC, SQL and NoSQL)
• Working knowledge of DevOps, cloud (Git flow, CI/CD,



Docker, AWS / Azure) and architecture
• Master’s degree or engineering school in Computer Science, Mathematics or Data Science, or equivalent
• Fluent English (client interactions and code reviews)
• The candidate will go through three interview stages.
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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, Kafka / RabbitMQ, Docker, Kubernetes, GitHub Actions, AWS / Azure

What we offer
• Challenging, real-world projects with major international clients, with autonomy and ownership
• A technical reference role: mentor AI Engineers and shape engineering standards
• Collaboration with lead engineers and access to cutting-edge technologies
• A dynamic, collaborative and innovation-driven environment
• Opportunities to take on greater responsibility within an international organization
• A high-performance culture: regular feedback and a strong focus on delivering tangible value

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