Product Engineer

Factorial; Barcelona; Hybrid; EUR 50,000 - 70,000; Full time

Job summary

Factorial is seeking a Product Engineer to help scale AI-powered business management software. You’ll contribute across the stack with Ruby on Rails and React, shipping features end-to-end and exploring AI-driven workflows.

You’ll join an engineering team that values curiosity, ownership, and impact, in a Barcelona or Madrid office setting with remote options. You’ll work on AI-native product development across Europe, growing your craft in a fast-paced, collaborative environment and helping

Qualifications

• 1–4 years of software engineering experience.
• Curious about AI and how it works, not just how to use it.
• Cares about whether what you built helped the user.
• Comfortable with Ruby on Rails and React.
• Strong communication and collaboration skills.

Responsibilities

• Ship features end-to-end from problem understanding to production validation.
• Work on AI-integrated systems and workflows.
• Evaluate AI features in production focusing on reliability and impact.
• Take real ownership of your work and continuously learn.

Skills

Ruby on Rails

React

AI curiosity

Cross-stack development

Education

BSc in Computer Science

Job description

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:

• Are genuinely curious about AI and excited to build with it, not just around it.
• Want to ship real things and learn fast, not wait until they feel "ready."
• Care about whether what they built actually helped, not what their title says.

As a Product Engineer you'll help us support and scale our AI Business Management Software across different domains. We’re on the lookout for people who get involved beyond the ticket, curious about why a feature exists, not just how to build it. Someone who asks questions, digs into the problem, and takes ownership of the outcome. This is not a maintenance role. We're moving fast, our domains are expanding, and there's real engineering work to do.

About The Team

Our Engineering team is the engine behind Factorial, crafting the tech that makes our AI 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.

You’ll work on a product used by thousands of companies across Europe, so your work has real, measurable impact. You’ll be in the middle of some genuinely new engineering territory: AI-native product development, not retrofitted AI. You’ll grow alongside a strong, experienced team that takes craft seriously!

What are we looking for?

• You have 1 to 4 years of experience in Software engineering and you're comfortable working across the stack. You don't need to have all the answers, but you ask good questions and follow through.
• You're curious about AI and have started exploring it, whether in side projects, coursework, or on the job. You want to understand how these systems actually work, not just use them.
• You care about outcomes. You want to know if the thing you built actually helped, and you're willing to go back and fix it if it didn't.
• You're comfortable, or eager to get comfortable, with Ruby on Rails and React.
• You communicate clearly and can explain what you're building and why without overcomplicating it.
• And you're a collaborative teammate: you ask for help when you need it and share what you learn.

What You’ll Be Doing?

• You’ll ship features end to end, from understanding the problem to writing the code to checking whether it worked in production.
• You’ll work alongside experienced engineers on AI-integrated systems: LLM-powered workflows, agentic features, and tools that help Finance teams move faster.
• Along the way you’ll learn how to evaluate AI features in production, not just build them, because reliability and user impact matter more than model complexity.
• You’ll take real ownership of your work. That means being curious about the "why," not just the "how." And you’ll grow fast. This is a team that moves quickly, shares knowledge openly, and expects you to level up.

How We Work (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, flexible approach.

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 space to do their best work.

At Factorial we don't evaluate you by years of experience but by your knowledge and skills.

We use our Career Path with a rubric framework where we define what is expected for each experience level and skill. This framework allows you to know your current level and what you need to keep growing. We love transparency, so our Career Path includes the salaries for each level, which we share during the first interview to ensure alignment.

Our Hiring Process

• Intro Call → Chat with our Talent Partner about your journey and goals.
• Hiring Manager Interview → Deep dive into your product mindset, teamwork, and problem-solving.
• Live Challenge → A collaborative technical exercise based on real-life problems.
• 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

Factorial is the AI for Business that knows companies, connects how work happens across the business, and turns that context into action.

Founded in Barcelona in 2016, we now have +1,700 employees serving more than 16,000 companies across 112 countries.

Factorial started with a simple idea: companies were spending too much time managing processes and not enough time doing the work they were hired to do: their best work.

But as companies grow, work gets more disconnected. More people, more tools, more information, and more time spent connecting the dots. Generic AI can answer questions, but it doesn’t know your company. Every time, you have to give it the context.

Factorial is different. Because it’s inside the company, it already knows how it works, including its people, processes, policies, and data. So you can ask it