Senior Machine Learning Engineer

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 modern Sofia office. This involves an office-first set up
• 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 and 10 paid days of educational leave which can be used to attend conferences and/or advance your career through further education
• Generous time off: 25 days of paid leave, plus one extra day per year of service (up to 35), along with public holidays and special leave options
• Peace of mind: additional health insurance and life insurance
• Stay active: on-site yoga and a co-sponsored Multisport card offering access to hundreds of sports facilities
• Meal support: benefit from a tax-free food voucher program plus flexibility via our Re:Benefits platform
• Easy commute: free shuttle buses connecting directly to Joliot-Curie metro station
• Break4me: 1-month sabbatical after 3 years of service
• Referral Bonus: earn additional rewards by referring talented individuals to join the SumUp team