Frontier Agentic AI Engineer — Santander AI Lab

About the role

Santander AI Lab (CDAIO) is seeking a Frontier Agentic AI Engineer based out of Madrid, Spain. The AI Lab is dedicated to applied innovation and is part of a global, high-impact brand undergoing a significant technological transformation.

Responsibilities

• Designing, building, and deploying production-grade agentic AI systems — multi-agent orchestration with real memory, planning, tool use, and error recovery.
• Developing and fine-tuning small and medium language models (SLMs) for regulated banking use cases, including custom evaluation frameworks and domain-specific benchmarks.
• Architecting and implementing MCP servers, A2A protocols, and federated API layers that allow AI agents to operate across the group’s multi-country infrastructure.
• Prototyping new ideas in two-week sprints: hypothesis, architecture, code, functional demo, one-pager.
• Collaborating with researchers, data scientists, and business stakeholders to translate complex technical concepts into tangible bank value — Alchemy-style transformations of legacy assets.
• Keeping the lab at the frontier: monitoring emerging research, evaluating new tools (Harness Engineering, Kiro, Windsurf, Devin), and integrating them into the lab’s workflow when they add real value.
• Producing clean, tested, observable code that can be handed off to the AI Science team for production scaling.

Requirements

• Professional Experience:
  • 4–8 years of software engineering or AI engineering experience, with at least 2 years building and maintaining LLM-powered systems in production environments.
  • Demonstrated hands-on experience designing and deploying multi-agent AI systems with real-world complexity.
  • Experience fine-tuning or adapting language models (SFT, LoRA, RLHF) for domain-specific tasks, including dataset curation and evaluation design.
  • Track record of delivering complete systems independently within tight timelines — from architecture decision to production-ready code.
  • Portfolio of real systems, not just demos.
  • Experience building and consuming REST APIs and integrating AI systems with enterprise data sources, cloud services and third-party platforms.
  • Prior experience in banking, fintech, or other regulated industries.
• Education:
  • Bachelor’s or Master’s degree in Computer Science, Software Engineering, Mathematics, Physics, or equivalent technical field.
  • Master’s degree or equivalent advanced qualification in AI, Machine Learning or related discipline.
• Languages:
  • English: professional working proficiency.
  • Spanish: professional working proficiency.
• Hard Skills:
  • Python: advanced proficiency.
  • Agentic AI frameworks: LangGraph, AutoGen, CrewAI, or Semantic Kernel.
  • LLM APIs and model ecosystems: Anthropic Claude API, OpenAI, open-source models (Llama, Mistral).
  • Cloud infrastructure: AWS (Bedrock, Lambda, SageMaker, S3).
  • Model evaluation and observability: you design evals, not just run them.
  • API development: FastAPI or equivalent.
  • DevOps basics: Docker, Git, CI/CD pipelines.
  • MCP (Model Context Protocol) server design and implementation.
  • SLM fine-tuning pipelines: vLLM, Ollama, Unsloth or equivalent for efficient domain adaptation.
  • Knowledge graphs or GraphRAG for structured knowledge retrieval in complex domains.
  • A2A protocol, x402 or AP2 for agentic payments or agent-to-agent communication.
  • Kubernetes, Terraform or equivalent for production-scale deployment.
• Soft Skills:
  • Radical autonomy: you arrive on Monday with your own priorities.
  • Builder’s mindset: when you encounter an interesting idea, your first instinct is to build a proof of concept, not write a slide about it.
  • Speed with judgment: you can deliver a functional demo in two weeks and know when a prototype is ready to transfer versus when it needs more work.
  • Frontier awareness: you read papers the week they drop. You have opinions about what Anthropic, Sakana AI and AWS are building.
  • Communication across roles: you can explain a complex agentic architecture to a business stakeholder and write a technical one-pager for the bank’s leadership team.

Benefits

• Competitive rewards: highly competitive salary with performance-based bonuses.
• Financial advantages: preferential banking terms, special interest rates on loans, life insurance, and more.
• Your health is our priority: access to BeHealthy, our global wellness programme.
• Family-friendly programs: childcare support and family-friendly programmes tailored to each life stage.
• Employee and family support: access to Santander Contigo, our program for employees and their families offering legal, emotional, and administrative advisory services.
• Additional benefits: gym/WellHub membership, medical centers in some of our facilities, meal subsidy, parking, shuttle service from various points in Madrid, as well as exclusive discounts and offers for Santander employees.

Pay

Competitive salary with performance-based bonuses.

Schedule

Hybrid working model—some days remote, some days onsite with your team—along with flexible hours.