Senior AI Backend Engineer

Team description SumUp Edge is our most ambitious product bet right now — an AI-powered co-pilot that transforms raw merchant data into proactive, real-time business insights. We're moving from being a payments processor to becoming an intelligent operating system for small businesses, and the backend infrastructure powering that shift needs to be world-class. This role sits at the very centre of that build: you'll architect the systems that connect our data platform, LLM orchestration layer, and merchant-facing APIs — and the work you do here will directly shape how millions of small businesses understand and grow their business. We are seeking a skilled and passionate Senior Backend Engineer to help lay the foundations of this vision. In this role, you will design, architect, and develop infrastructure and systems that enables AI products to be successful, and that turn complex, real-world merchant data into scalable, production-grade information for AI solutions. Your expertise in backend and infrastructure combined with AI will be instrumental in shaping the intelligence layer and building sustainable infrastructure that powers our next generation of products. You will collaborate closely with machine learning engineers, data scientists, product managers, and business stakeholders to translate business challenges into robust, high-impact AI capabilities. Your work will directly influence how small businesses operate, compete, and grow, positioning SumUp at the forefront of applied AI in fintech. What you’ll do Architect, design, develop and deploy our AI solutions and systems in production environments, ensuring reliability, high performance and scalability. Design and build the orchestrator service that coordinates AI components, data flows, and external services to deliver reliable, real-time insights to merchants Develop and maintain scalable ETL pipelines or MCPs that process and sync heterogeneous data (text, images, audio) from various sources into the AI system Build and optimise the LLM Gateway infrastructure, including authentication, rate limiting, load balancing, and vector database management for the RAG system Create robust, high-performance APIs capable of handling multimodal data structures and high-volume requests, ensuring low-latency and production-grade reliability Implement observability tooling — including telemetry, logging, and tracing — to support auditing, evaluation, and continuous improvement of AI interactions Mentor backend engineers on the team, contributing to engineering standards, code reviews, and a culture of technical excellence Collaborate and communicate closely with data scientists, product managers, developers and other business stakeholders to bring state-of-the-art AI solutions to Customer Support, enhancing customer experience and improving operational efficiency. You’ll be great for this position if you have Bachelor's or master's degree in Computer Science, Engineering, or a related field. +6 years of experience developing software products (if they are ML or AI related is a plus) Advanced proficiency in Python, with hands-on experience building and scaling backend systems in production environments using tools like Kubernetes, Docker, Airflow, and Spark. Strong knowledge of cloud infrastructure (AWS, S3) and CI/CD practices, with a track record of shipping reliable, maintainable systems. Experience designing APIs and working with distributed data systems and message brokers such as Kafka or RabbitMQ. Comfort working at the intersection of backend engineering and AI — including familiarity with LLMs, GenAI tooling, and machine learning concepts. Experience with status monitoring using cloud-native tools or 3rd party (e.g. Prometheus, Cloudwatch, ...) and LLM traceability Excellent communication and collaboration skills to work effectively in cross-functional teams. Ability to adapt to a fast-paced, dynamic work environment and quickly learn new technologies and techniques. Stron