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
- Are obsessed with building and shipping fast
- Care about real impact, not hierarchy or titles

If that sounds like you, keep reading.
The Team
The Operations domain sits at the core of Factorial. This is where we build the systems that run the day-to-day reality of work for thousands of companies, systems that must be accurate, compliant and reliable.
Our teams own business-critical workflows such as:
- How employee time is tracked, planned, and managed
- How the employee journey is modeled from onboarding to offboarding
- How companies represent their organizational structure
- How compensation and payroll data are calculated and trusted

Our mission is to turn operational complexity into simple, AI-powered experiences, helping companies run smoothly at scale while keeping humans in control of what matters most.
What You’ll Do




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

We define clear specifications before shipping — including expected behaviours, constraints, and success criteria — and use them to guide implementation, iteration and evaluation using most powerful LLMs.
- Design and implement AI Skills

Create reusable, well-scoped AI capabilities that can automate and take actions safely within Factorial’s workflows.
- Develop and maintain evaluation frameworks (Evals)

Measure quality, correctness and reliability of AI outputs using automated and human-in-the-loop evaluations to ensure continuous improvement in production.

Build systems that ground AI responses in trusted, up-to-date company data, balancing probabilistic models with deterministic sources of tru

📌 Ai Product Engineer (Barcelona)
🏢 Factorial
📍 Barcelona