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Staff Software Engineer
Job Location:
Yearly Salary:
Posted:
23 October 2026 (13 hours ago)
Posted:
Application Deadline:
20 January 2027
Application Deadline:
Vacancies:
1 Vacancy
Vacancies:
Job Summary
Hello!
Were looking for a Staff Software Engineer to help build AI-native features into Factorials product. Not a researcher not a model trainer: a product engineer who builds with LLM APIs the same way we build with any other API shipping real features to real customers in production.
At Factorial being a Staff Engineer means leading technical initiatives and working very closely with Product not operating at arms length from the roadmap. Youll be writing Rails and React designing systems and shipping product hand in hand with Product and Design. AI is the domain youll work in not a different job.
Ready to be part of the challenge
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.
Were 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 were building on top of that: agentic workflows LLM-integrated features systems that behave probabilistically rather than deterministically.
What are we looking for
What Youll Be Doing
One honest note: if youre mainly looking to do model training fine-tuning or applied ML research this probably isnt the right role for you. Were a product engineering team working with LLM APIs and agentic systems not a team building models from scratch.
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. Thats why our Engineering Teams follows an office-first flexible schedule.
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 dont 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
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 1700 employees serving more than 16000 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 doesnt know your company. Every time you have to give it the context.
Factorial is different. Because its inside the company it already knows how it works including its people processes policies and data. So you can ask it to do real work from screening candidates and managing expenses to answering questions and creating reports.
AI isnt the goal. Giving people back their time is.
When work changes so do we.
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
Wanna learn more about us Check our website!
Perks of being part of Factorial
Were looking for a Staff Software Engineer to help build AI-native features into Factorials product. Not a researcher not a model trainer: a product engineer who builds with LLM APIs the same way we build with any other API shipping real features to real customers in production.
At Factorial being a Staff Engineer means leading technical initiatives and working very closely with Product not operating at arms length from the roadmap. Youll be writing Rails and React designing systems and shipping product hand in hand with Product and Design. AI is the domain youll work in not a different job.
Ready to be part of the challenge
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.
Were 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 were building on top of that: agentic workflows LLM-integrated features systems that behave probabilistically rather than deterministically.
What are we looking for
- You have solid depth in both backend and frontend software engineering
- Youve 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
- Youve integrated LLM APIs into product features and shipped them to real users. This is about building with AI not training or fine-tuning models
- Youre seen as a technical and cultural leader and you hold the bar high
- You push back on process that doesnt serve the team from hiring to deployment
- You drive adoption of new abstractions and make sure others can actually use them
- Youve 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 Youll Be Doing
- Lead technical initiatives. As a Staff Engineer youll set technical direction for meaningful chunks of the roadmap not just execute against it. Youll make the calls on architecture and approach and be accountable for how they play out.
- Work very closely with Product. This isnt occasional collaboration its a tight ongoing partnership. Youll shape what gets built alongside Product and Design from the earliest conversations not just take specs and implement them.
- Own systems end to end. From the first conversation about a problem through production rollout to long-term maintenance. Including the unglamorous parts.
- Stay close to customers. The best technical decisions come from understanding real problems so youll talk to customers directly and bring that context back into how we build.
- Help define how we build AI features at scale. Were still figuring out what great AI product engineering looks like at Factorial and thats part of the job. Youll help shape how we design build and run AI-native product experiences so theyre reliable compliant and genuinely useful.
- Champion spec-driven development. Push for a culture where teams define what good looks like before they build: expected behaviors constraints edge cases success criteria. Then use those specs to move fast without breaking things.
- Build things other teams can reuse. Rather than a patchwork of one-off AI experiments youll build shared components other product domains can actually use: scalable secure and easy to govern.
- Design and evolve AI Skills. Drive the creation of modular reusable AI skills that automate real workflows and take safe traceable actions inside Factorials ecosystem especially where finance is involved.
- Build the tooling that keeps AI features trustworthy. Getting an AI feature to production is one thing. Keeping it reliable once real customers depend on it is another. Youll 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. Help define how we combine LLM outputs with deterministic sources of truth balancing flexibility with accuracy and compliance.
- Raise the bar across the company: Whether its mentoring hiring or pushing for better practices youll leave the engineering culture better than you found it
One honest note: if youre mainly looking to do model training fine-tuning or applied ML research this probably isnt the right role for you. Were a product engineering team working with LLM APIs and agentic systems not a team building models from scratch.
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. Thats why our Engineering Teams follows an office-first flexible schedule.
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 dont 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 1700 employees serving more than 16000 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 doesnt know your company. Every time you have to give it the context.
Factorial is different. Because its inside the company it already knows how it works including its people processes policies and data. So you can ask it to do real work from screening candidates and managing expenses to answering questions and creating reports.
AI isnt the goal. Giving people back their time is.
When work changes so do we.
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: Were 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.
Wanna learn more about us Check our website!
Perks of being part of Factorial
- High growth multicultural and friendly environment
- Competitive ESOP plan
- Alan as private health insurance
- Healthy life with Wellhub (Gyms pools outdoor classes)
