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. Join us as a Founding Engineer in a brand-new Factorial spinoff.

We’re building a new startup inside Factorial, starting from scratch, with real backing and a clear target: 0 to 100 million by 2030. It's ambitious, and that's the point. The focus is on rethinking how companies manage workflows, org charts, policies, and analytics, the operational core of what Factorial does.

But this isn't an internal project. It’s a spinoff with its own identity, its own pace, and its own team. The advantage of doing this inside Factorial is that we’re not starting cold. We have 17,000+ existing customers, a dedicated GTM team, and the infrastructure to move fast.

You’ll be joining at day zero, but with a real runway. In terms of what we’re building, the tech matters less than you’d think.

We care about your ability to move fast, make good decisions with incomplete information, and build things people actually want to use. That said, strong Ruby on Rails experience on the backend and solid React or TypeScript on the frontend will go a long way. If you’ve ever wanted to work in a small, scrappy team with the energy of an early‑stage startup but without the typical early‑stage uncertainty, this is that opportunity.

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 a 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.

What are we looking for?





You have an entrepreneurial mindset and genuinely enjoy the early stage of building something from scratch.

You’ve shipped AI-powered features and know that evaluating them in production is the hard part, not building them.

You think about reliability and user friction before model complexity.

You’re comfortable reviewing agentic workflows and have opinions about LLM architecture tradeoffs.

Not just theoretical ones; you treat AI features as hypotheses and build, deploy, measure, adjust.

You own that whole loop, not just the build part.

You can break down non‑deterministic outputs into something the rest of the team can reason about and act on.

You’re comfortable working with Ruby on Rails & React and understand how to integrate AI models into scalable, cloud‑native environments.

You help teammates who are transitioning from deterministic to probabilistic thinking, not by lecturing, but by working through it together.

4+ years in software engineering, with some track record (or serious curiosity) around shipping AI features.

You can explain a complex technical decision in English to someone who doesn’t write code clearly, without condescension.

What you’ll be doing?

Founding Engineer taking ownership of big initiatives and being interested in the outcome, not just the output.

Establishing goals and a quarterly roadmap with the team, with special attention to the technical needs of our domain.

Participating in customer calls to learn about their pains & needs.

Reviewing code daily and getting feedback on your own code at every pull request from all team members, including juniors.

Learning from the entire team, both on technical topics (performance, architecture…) and core skills, in an environment driven by engineering quality.

Mentoring junior team members and helping them learn from your experience.

How We Work





(Barcelona Office) At Factorial, we believe the best products are built when people come together, in person to collaborate, challenge ideas, and move fast.

Our Engineering Teams follow an office‑first, adaptable schedule. We work on‑site several days a week, using that time to connect, align, and innovate as a team.

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.

About Factorial We’re building the leading AI Business Management Software for companies of all sizes. Our platform centralises key workflows across HR, Finance, Talent, Operations, and IT, freeing teams from manual processes so they can focus on what really matters: leading, growing, and taking care of their people.

With over 1,500 employees across Europe, Asia, Africa, and America, we are one of Europe’s fastest-growing SaaS companies, proudly headquartered in Barcelona. If you’re excited to shape the future of business management technology, we’d love to meet you.

We believe in diverse talent: we welcome applicants from all backgrounds and strongly encourage people of diverse experiences and identities to apply. We believe in inclusion: we are committed to equal opportunities and actively promote workplace inclusion of people with disabilities. If you would like to learn more about our inclusive recruitment processes, you are welcome to indicate so optionally and we will share additional information with you.

Our Values

We own it: We take responsibility for every project.

We make decisions, not excuses.

We learn and teach: We're dedicated to learning something new every day and, above all, share it.

We partner: Every decision is a team decision.

We trust each other.

We grow fast: We act fast.

We think that the worst mistake is not learning from them.

Perks of being part of Factorial

High growth, multicultural and friendly environment

Alan private health insurance

Healthy life with Wellhub (Gyms, pools, outdoor classes)

Save expenses with Cobee

Language classes

Breakfast in the office and organic fruit

Food discounts with Nora

Pet Friendly

📌 Founding Engineer (Madrid)
🏢 Factorial Hr
📍 Madrid