Personio's intelligent HR platform helps small and medium-sized organizations unlock the power of people by making complicated, time-consuming tasks simple and efficient. Our team of 1,500 Personios is building user-friendly products that delight our 15,000+ customers and their 1.5 million employees. Ready to make an impact from day one?

The Role

This role requires 2 days per week in the office and is based in Madrid.

Join us to shape the future of software in the underserved and high-impact HR technology industry. Your work will have a direct and tangible impact on customers, offering ownership and the chance to make a meaningful difference. As we prepare for significant growth, you'll face exciting challenges and have the opportunity to influence our path toward becoming one of the world's leading tech companies.

Join our AI team and work as part of a diverse engineering team to build and deliver production-quality services using Python and Kotlin. You will deliver LLM and ML-powered projects with real business impact. Work in a lean, well-supported environment focusing on real use cases and improving our users experience. This is a high visibility within the organisation to build impactful products.

What You’ll Do

• Strong backend software engineering capabilities in Kotlin and Python alongside deep machine learning expertise.

• Own the complete pipeline: from model development and evaluation through to the production infrastructure, APIs, and monitoring systems that deliver AI capabilities to end-users at scale.

• Design, develop, and deploy robust machine learning and AI systems for a range of products and use cases, including generative AI and LLM-based solutions.

• Leverage cloud platforms (AWS + Snowflake) and ML infrastructure (e.g., SageMaker, feature stores) for scalable deployment.

• Collaborate with cross-functional teams (Product, Customer Experience, and other engineering teams) to deliver AI-driven features and insights.

• Ensure all ML/AI solutions adhere to best practices in data privacy, security, and ethical standards.

• Contribute to a culture of technical excellence, knowledge sharing, and continuous learning.

What You Need to Succeed

• University degree in Computer Science, Machine Learning, Data Science, or a related field.

• 3+ years' experience building and deploying production-grade machine learning models.

• 1+ years' experience working with a team to build and deliver production-quality backend services.

• Strong software engineering mindset — ability to write clean, reusable, and scalable code in Python, with experience in object-oriented languages and backend systems. You'll work with both Python and Kotlin in this role.

• Experience integrating ML/AI models into production software systems.

• Solid understanding of MLOps practices, CI/CD pipelines, and automated testing frameworks.

• Experience working with backend teams and deploying end-to-end products.

• Experience with NLP or generative AI techniques.

• Ability to evaluate LLM-based systems for accuracy, reliability, and business impact.

• Hands-on experience with LLM agent frameworks and orchestration patterns.

Nice to Have

• Background in data science: comfort with experimentation, A/B testing, and measuring ROI/impact of ML projects (not just accuracy).

• Experience with NLP or generative AI techniques.

• Familiarity with cloud-based ML infrastructure (AWS, Snowflake, SageMaker, etc.).
  

Why Personio

Personio is an equal opportunities employer, committed to building an integrative culture where everyone feels welcomed and supported. We embrace uniqueness and understand that our diverse, values-driven culture makes us stronger. We are proud to have an inclusive workplace environment that will foster your development no matter your gender, civil status, family status, sexual orientation, religion, age, disability, education level, or race.

At Personio, we value in-person collaboration while also offering flexibility. This role is office-based, with 2 days per week required in your contracted office location. The remaining days can be worked from home or in the office if you prefer. In addition, you’ll have 20 Flex Days per year to work remotely from other locations.

Aside from our people, culture, and mission, check out some of the other benefits that make Personio a great place to work:

• Receive a competitive reward package – reevaluated each year – that includes salary, benefits, and pre-IPO equity
  

• Enjoy 28 days of paid vacation, plus an additional day after 2 and 4 years
  

• Make an impact on the environment and society with 1 (fully paid) Impact Day
  

• Receive generous family leave, child support, mental health support (including 24 sessions per year with Oli for yourself and 10 sessions for a significant other), and sabbatical opportunities
  

• We enjoy gathering for meals, cultural initiatives, and events like local Summer Sessions and year-end celebrations. There's also healthy snacks, drinks, and a weekly catered lunch.