Senior Machine Learning Engineer II

About the team

Our Global Operations team is on a mission to build the best customer experience in fintech, and AI is at the heart of how we get there. As part of our dedicated AI team, you'll sit at the intersection of machine learning engineering and real-world product impact, building the models and systems that power intelligent customer support for over 4 million merchants worldwide. This isn't a research role; it's a hands-on engineering position where the work you ship directly shapes how merchants experience SumUp every day.

What you'll do

• Architect, build, and deploy AI solutions into production, ensuring they're reliable, performant, and built to scale
• Design and maintain ML infrastructure and pipelines that support efficient data processing, model training, and serving
• Fine-tune and optimise machine learning models for accuracy, efficiency, and scalability in large-scale environments
• Collaborate closely with data scientists, product managers, and backend engineers to translate business needs into working AI solutions
• Apply strong engineering standards across your work, including version control, CI/CD, and testing frameworks
• Collect, preprocess, and prepare large text datasets to support high-quality model training and evaluation

You'll be great for this role if

• Experience building and deploying scalable machine learning or AI solutions in large-scale production environments, with a focus on reliability and performance
• Strong knowledge of AI product development, including chatbot assistants, RAG systems, or similar conversational AI applications
• Advanced proficiency in Python, with hands-on experience using MLOps tooling such as MLflow, Kubeflow, Airflow, or Langfuse
• Comfort working across the full ML workflow, from feature engineering and data pipelines through to model serving, monitoring, and alerting
• Experience deploying ML models using cloud platforms such as AWS, GCP, or Azure, alongside familiarity with Docker, Git, and API integrations

Why you should join SumUp

• 🌎 Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide, from our Barcelona office. This involves an office-first setup
• 🌈 Commitment to Diversity and Inclusion: be part of a workplace that values and promotes diversity, fostering an inclusive environment where everyone's perspectives are respected and embraced
• 🚀 Enrolment onto our Virtual Stock Option programme: you will own a stake in SumUp's future success
• 📚 A dedicated annual L&D budget of €2000 for your individual development, which can be used to attend conferences and/or advance your career through further education
• 🏖 Generous time off: enjoy 23 days of paid leave plus public holidays and special leave days
• 🥗 Subsidised restaurant tickets (Edenred) and office breakfast on Mondays
• 🌴 Break4me: 1-month sabbatical after 3 years of service
• 🔗 Referral Bonus: earn additional rewards by referring talented individuals to join the SumUp team

About SumUp

Be empowered to do more that matters.

At SumUp, we're on a mission to empower small businesses across the globe by providing simple and affordable tools that allow them to thrive. Today, over 4 million businesses in 37 markets rely on SumUp as their financial partner to manage payments, finance and customer relationships.

Our commitment to small businesses is reflected in our diverse team of over 3,000 SumUppers from over 90 nationalities, united by global collaboration and an innovative mindset. Our core values lay the foundation for who we are and what we stand for, shaping our work culture and driving our success. We foster inclusivity and a continuous learning culture, providing a safe space for personal and professional growth. Our differences make us unique and strong as we strive to create an environment where everyone belongs and feels supported, no matter how they identify.

SumUp is proud to be an Equal Employment Opportunity employer, actively seeking and embracing diversity in our workforce. We don't make hiring or employment decisions based on race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. Our commitment extends beyond recruitment to creating a safe and respectful workplace where harassment of any form is strictly prohibited. Discover more about our culture and opportunities on our careers website, and follow our journey on LinkedIn, Instagram, and TikTok.