Senior Software Engineer, AI (Spain)

You will join a small, highly autonomous cross-functional team to build AI agents that fundamentally transform how operations work at scale. Instead of writing bespoke software for every workflow, we are developing an agent platform that can read operational knowledge, reason about it in context, and execute tasks end-to-end. This approach allows us to scale complexity through knowledge and reasoning, rather than simply through code.

This is an opportunity to join a foundational team, which currently consists of fewer than five engineers. The work spans critical areas including LLM-powered agent design, robust backend service architecture, tool and integration development, and sophisticated knowledge infrastructure.

We are seeking a Senior Software Engineer with a strong passion for building AI-native systems in a product environment. The ideal candidate will be able to take ownership of large segments of the technology stack, make pragmatic technical decisions in ambiguous and emerging territory, and consistently ship high-quality, production-ready systems that our users rely on every day.

You are comfortable in a fast-paced, early-stage environment. You demonstrate a "scrappy" and resourceful approach, proactively identifying solutions and unblocking yourself without needing a fully defined path.

You are pragmatic and balance quality with speed. You understand when to optimize for long-term durability and when to iterate quickly. You prioritize pragmatism over being overly precious about code, but never compromise on quality in a way that creates future issues.

You are product-minded. You look beyond the immediate task, seeking to understand the "why" behind the build and questioning whether it's the right product solution. You are comfortable contributing product thinking alongside engineering work.

You demonstrate a strong ownership mindset. You are proactive, identify gaps, and drive initiatives to completion without waiting for explicit instructions. When encountering issues or ambiguity, you address them directly.

You possess strong backend engineering fundamentals. You can confidently design, build, and operate production systems.

You are curious and eager to develop expertise in AI and LLMs. While deep research is not required, you are motivated to build practical, real-world products using these tools, specifically focusing on agent systems.

Golang, Ruby on Rails, Javascript, Java, C#, Python, VueJS, MySQL, Kafka, AWS, Git, Memcache, Redis, ElasticSearch, Docker, Terraform, Kubernetes, CircleCI, DataDog

The base wage range for this position based in Spain is 111,000-143,000 EUR.

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Actual compensation is based on multiple factors that are unique to each candidate, including and not limited to skill set, level of relevant experience, and specific work location. Salary ranges for positions based in other locations may differ based on the cost of labor in that location.

For more information about Justworks’ Total Reward Philosophy, including all of the perks and benefits we are proud to offer our team members, please visit Total Rewards @ Justworks .

Justworks is committed to maintaining a workplace where diversity of identity, culture, and life experience is the norm and is celebrated authentically and respected consistently. Diversity in our work, our people, and our product drives creativity and innovation, entrepreneurial leadership and integrity, competitiveness, and collaboration throughout our business and in the market. We depend on our differences to make our team stronger, our workplace more dynamic, and our product accessible to all of our customers.

We’re proud to be an equal opportunity employer open to all qualified applicants regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital or familial status, disability, pregnancy, gender identity or expression, veteran status, genetic information, or any other legally protected status. Justworks is fully dedicated to providing necessary support to candidates with disabilities who may require reasonable accommodations. We also provide reasonable accommodations to employees based on their sincerely held religious beliefs, as well as for other covered reasons consistent with applicable federal, state, and local laws. If you're in need of a reasonable accommodation, please reach out to us at accommodations@justworks.com . Your comfort and success matter to us, and we're here to ensure an inclusive experience.

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