We're looking for a Staff Software Engineer to help build AI-native features into Factorial's product. You'll be writing Rails and React, designing systems, and shipping product hand in hand with Product and Design. "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. ðYou have solid depth in both backend and frontend software engineering You've shipped real products to production, not just prototypes or proofs of concept You understand APIs, cloud platforms (AWS, Azure, or GCP), and system design well You've integrated LLM APIs into product features and shipped them to real users. This is about building with AI, not training or fine-tuning models You're seen as a technical and cultural leader, and you hold the bar high You push back on process that doesn't serve the team, from hiring to deployment You drive adoption of new abstractions and make sure others can actually use them You've shipped things that made a measurable difference, at work or on the side You lead key technical decisions and create things others across the company build on You communicate clearly in English; Spanish is a plus What You'll Be Doing? As a Staff Engineer, you'll set technical direction for meaningful chunks of the roadmap, not just execute against it.

This isn't occasional collaboration, it's a tight, ongoing partnership. Keeping it reliable once real customers depend on it is another. You'll build monitoring and quality tooling (automated and human-in-the-loop) so teams get a real signal on quality.

Ground AI features in data we actually trust. Whether it's mentoring, hiring,



or pushing for better practices, you'll leave the engineering culture better than you found it One honest note: if you're mainly looking to do model training, fine-tuning, or applied ML research, this probably isn't the right role for you. We're a product engineering team working with LLM APIs and agentic systems, not a team building models from scratch.

How We

Work ð» (Barcelona or Madrid Office)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, versátil schedule. 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 space to do their best work.

Our Hiring Process Intro Call

Chat with our Talent Partner about your journey and goals.

Final Coffee

Chat A relaxed conversation with our CTO & VP of Engineering to explore our vision, culture, and your growth. The whole process is remote, using videoconferencing tools!

About

Factorial ðAt Factorial, we're building the leading AI Business Management Software for companies of all sizes. Our platform centralizes 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.

We own it: We take responsibility for every project. We're dedicated to learning something new every day and, above all, share it. Perks of being part of Factorial ðHigh growth, multicultural and friendly environment Alan as 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 Much more that we'll spill during the interview process!

📌 Staff Software Engineer - Full Stack (Barcelona)
🏢 Factorial Hr
📍 Barcelona