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:

1. 🧠 Treat AI as central to their craft
2. ⚡ Are obsessed with building and shipping fast
3. 🎯 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:

1. How employee time is tracked, planned, and managed
2. How the employee journey is modeled from onboarding to offboarding
3. How companies represent their organizational structure
4. 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:

1. Build product using Spec Driven Development
2. 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.
3. Design and implement AI Skills
4. Create reusable, well-scoped AI capabilities that can automate and take actions safely within Factorial’s workflows.
5. Develop and maintain evaluation frameworks (Evals)
6. Measure quality, correctness and reliability of AI outputs using automated and human-in-the-loop evaluations to ensure continuous improvement in production.
7. Apply Retrieval-Augmented Generation (RAG)
8. Build systems that ground AI responses in trusted, up-to-date company data, balancing probabilistic models with deterministic sources of truth.
9. Design human-in-the-loop and agentic workflows
10. Combine LLMs, rules, and user oversight to automate real business processes while keeping humans in control of critical decisions.
11. Own systems end-to-end
12. From problem definition and system design to shipping, monitoring and iteration in production.
13. Stay close to our customers
14. We have a strong customer-centric mindset: engineers regularly join customer calls, reviews, and feedback sessions to deeply understand real workflows, pain points, and constraints — ensuring we build the right solutions to real problems, not assumptions.
15. Collaborate closely with Product and Design
16. Shape how AI is embedded into core user experiences — not as a feature, but as part of the workflow.
17. Share knowledge and raise the bar
18. Mentor peers, document learnings, and contribute to Factorial’s AI engineering best practices.

Who This Is For 🧠

Your title matters less than your mindset.

You might be mid, senior, or staff, what we care about is:

1. AI as a habit: you’ve built real AI-powered systems or workflows (not just experiments)
2. Proven impact: shipped projects, side projects, or contributions that made a measurable difference
3. Product-first thinking: you design complete experiences, not just isolated components
4. 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:

1. Solid software engineering fundamentals (any language — Python is common)
2. Experience shipping real products to production
3. Knowledge of APIs, cloud platforms, and system design
4. A fast learning curve with new tools and technologies

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

How We Work 🏢

1. Office-first in Barcelona & Madrid, with 20% remote flexibility
2. A people-first, high-trust culture built on radical candor and ownership
3. A multicultural team (40+ nationalities) building the next generation of business management software