Hello! Do you want to help us build the platform that connects Factorial to the rest of the software world, with strong engineering foundations today and AI as a growing part of how we work tomorrow?

We’re looking for engineers who:

- Care about the maturity and quality of what they ship, more than the specific stack they use
- Care about whether the thing they built actually worked — not what their title says

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 are 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, though we’re open to engineers from other stacks – what matters most to us is the maturity of your development practice.

The API & Integrations team addresses particular challenges at Factorial. We sit at the intersection between product and platform. We own product surface while we also design developer experiences for internal and external developers of integrations.

- We build tools for Factorial product teams to publish in our extensive public API.
- We build an integrations framework to achieve the best user experience and developer experience when using integrations. Several Factorial products already use this framework, and we keep expanding it.
- We enable our developer partners to extend Factorial and live the best developer experience. With the acquisition of YepCode, we’re laying the groundwork to bring AI further into how we build integrations.

What You’ll Do

As an engineer on the API & Integrations team,



your main focus will be owning the development of our public API and integrations framework end‑to‑end, from problem definition and system design to shipping, monitoring, and iteration in production.

- Own systems end‑to‑end from problem definition, system design to shipping, monitoring, and iteration in production.
- Collaborate closely with Product and Design, shaping how the API and integrations framework serve real user needs.
- Work with a real cross‑product consistency challenge: keep the same user and integration experience across verticals (ATS, payroll, ERPs...), all tied to Factorial’s design system.
- Stay close to our customers – engineers regularly join customer calls, reviews, and feedback sessions to deeply understand real workflows, pain points, and constraints.
- Share knowledge and raise the bar – mentor peers, document learnings, and contribute to Factorial’s engineering best practices.
- Take ownership of AI as it takes shape – define AI skill evaluation frameworks, RAG, and agentic workflows as part of the YepCode roadmap.

What We’re Looking For

- Development maturity: write solid, well‑tested, production‑grade code and own a system end‑to‑end.
- Proven impact: shipped projects, side projects, or contributions that made a measurable difference.
- Product‑first thinking: design complete experiences, not just isolated components.
- Speed & adaptability: experiment, learn, and iterate fast.
- An abstraction mindset:



experience working with legacy/monolithic systems and a track record of creating reusable, generic frameworks that serve multiple teams and languages.

Bonus Points

Bonus points if you’ve worked with LLMs, skill‑based agents, MCP, or other AI protocols.

Technical Foundation (Not Strict Requirements)

- Strong software engineering fundamentals and development maturity, in any language.
- Experience shipping real products to production.
- Knowledge of APIs, cloud platforms, and system design.
- A fast learning curve with new tools and technologies.

How We Work (Barcelona Office)

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 follow an office‑first, adaptable schedule.

We work on‑site several days a week, using that time to connect, align, and innovate. We also support remote work when it makes sense – for deep work, personal needs, or a change of scenery.

We evaluate you by your knowledge and skills, not years of experience. We use a Career Path rubric to define expectations for each level and skill, and we include salaries for each level during the first interview.

Equal Opportunity Statement

We welcome applicants from all backgrounds and strongly encourage people of diverse experiences and identities to apply. We are committed to equal opportunities and actively promote workplace inclusion of people with disabilities.

Perks of Being Part of Factorial

- High growth, multicultural and friendly environment
- Alan private health insurance
- Wellhub wellness: gyms, pools, outdoor classes
- Discounts with Cobee, Nora
- Language classes
- Breakfast in office and organic fruit
- Pet friendly environment

#J-18808-Ljbffr

📌 Staff AI Engineer - API & Integrations Team (Barcelona)
🏢 Factorial
📍 Barcelona