Full Stack Engineer - Knowledge Base Team

About the role

Santander's Chief Data & Artificial Intelligence Officer (CDAIO) division is looking for a Full Stack Engineer based in Madrid to join its Knowledge Base team. You will build and operate secure, scalable applications, APIs and user experiences that turn enterprise data into trusted knowledge for RAG, GraphRAG, semantic search and AI agents, working with AI, Data, Cloud, DevOps, Product and Security teams.

Key responsibilities

• Design and build full stack applications, backend services, APIs and web interfaces for the Knowledge Base Platform.
• Develop data-to-knowledge workflows covering ingestion, chunking, embeddings, metadata, entities, relationships, retrieval and validation.
• Build RAG and GraphRAG services combining vector search, graph traversal, reranking, grounding and citations.
• Create secure integrations and tools for AI agents, including MCP-based interfaces.
• Deliver cloud-native solutions on AWS using containers, serverless and event-driven patterns.
• Apply strong engineering practices across testing, security, observability, CI/CD, reliability and cost.
• Collaborate across teams and contribute to technical design decisions and platform evolution.

Required profile

• 5+ years in full stack, backend, cloud, platform or AI engineering.
• Experience building and operating production-grade distributed systems, APIs or cloud applications.
• Hands-on experience with LLM applications, RAG, semantic search or intelligent automation.
• BSc or MSc in Computer Science, Software Engineering or a related field, or equivalent practical experience.
• Spanish proficiency; experience in a regulated enterprise environment, high-level English and knowledge of knowledge graphs, GraphRAG, agent frameworks, Amazon Bedrock or MCP are preferred.

Required skills

• Python, FastAPI, Django or Flask; React, TypeScript, JavaScript, HTML and CSS.
• APIs, microservices, distributed systems, security, testing, CI/CD and observability.
• AWS, Docker, Kubernetes and infrastructure-as-code.
• RAG, embeddings, vector search, reranking, grounding and evaluation.
• Relational, document, vector, graph or search databases.

What we offer

• Hybrid working model with flexible hours.
• Access to Santander Open Academy courses.
• Performance-based bonuses, preferential banking terms and wellness programmes.
• Childcare support, employee family advisory services and extra benefits such as gym membership, meal subsidy and parking.