AI Engineer - API & Integrations Team; Coruña

Product AI Engineer at Factorial

Hello! Do you want to help us redefine how AI powers the future of Business Management software, not as an add-on, but as a core part of how people work, decide and grow? We're looking for engineers who:
Treat AI as central to their craft, not a feature to bolt on later Want to build and ship, not debate and document Care about whether the thing they built actually worked — not what their title says. Ready to be part of the challenge?

About the team Our Engineering team is the engine behind Factorial, crafting the tech that makes HR simple, fast, and reliable for thousands of companies. If you love solving hard problems and want to build something that truly matters, come build it with us. We're a team of 200+ Product Engineers building Business Management solution that actually works for the people using it.

Our core stack is Ruby on Rails and React but the interesting work right now is what we're building on top of that: agentic workflows, LLM-integrated features, systems that behave probabilistically rather than deterministically. The API & Integrations team addresses particular challenges  sit at the intersection between product and platform. We own product surface while we also design developer experiences for internal and external developers of integrations.

We build tools for Factorial product teams to publish in our extensive public API. We build an integrations framework to achieve the best user experience and developer experience when using integrations. Several Factorial products are already using this framework. And we keep expanding it. We enable our developer partners to extend Factorial and live the best developer experience. With the acquisition of Yep Code, we will be boosting how we build integrations, placing AI at the center of the process.

Our mission is not only to unblock markets that rely on a fragmented market of different external software (payroll software solutions, ERPs, cloud-based identity services, etc.), but also to lower the barrier so that anybody (even HR managers) is able to create new integrations.

As a Product AI Engineer at Factorial, you'll help define and build the next generation of our AI-native product using modern AI development practices. You will:

• Build product using Spec Driven Development
• Design and implement AI Skills
• Develop and maintain evaluation frameworks (Evals)
• Apply Retrieval-Augmented Generation (RAG)
• Design human-in-the-loop and agentic workflows
• Own systems end-to-end
• Stay close to our customers
• Collaborate closely with Product and Design
• Share knowledge and raise the bar

Your title matters less than your mindset. You might be mid, senior, or staff. What we care about is: AI as a habit: you've built real AI-powered systems or workflows (not just experiments) Proven impact: shipped projects, side projects, or contributions that made a measurable difference Product-first thinking: you design complete experiences, not just isolated components Speed & adaptability: you experiment, learn, and iterate fast

Bonus points if you've worked with: LLMs, skill-based agents, MCP, or other AI protocols

Technical Foundation (Not Strict Requirements) Strong candidates often have:
Solid software engineering fundamentals (any language — backend, frontend, ML) Experience shipping real products to production Knowledge of APIs, cloud platforms, and system design A fast learning curve with new tools and technologies

We care far more about what you've built than the stack you used.

At Factorial, we believe the best products are built when people come together, in person to collaborate, challenge ideas, and move fast. That's why our Engineering Teams follows an office-first, flexible schedule. We work on-site several days a week, using that time to connect, align, and innovate as a team. However, we also understand the importance of focus and flexibility, so we support remote work when it makes sense - whether for deep work, personal needs, or just a change of scenery.

This balance helps us stay agile, creative, and closely connected, while giving everyone the…