(Senior) AI Engineer (m/f/d)

ABOUT US
Unzer is a leading European fintech company with a mission to simplify international payments for e-commerce and retail businesses. Our brand was formed from 13 companies that now contribute to building a unique product covering the entire payment flow.  
At Unzer, we are driven by the belief that customers should enjoy a seamless shopping experience, no matter where they choose to shop. We are a team of over 700 experts from 55 different nationalities, dedicated to creating a state-of-the-art unified commerce platform. Our goal is to enable businesses to delight their customers with a seamless payment experience. 
Whether you're a tech enthusiast, payment expert, or a dedicated support professional, we are looking for individuals who are passionate about making a difference.   Our offices: We are based across Austria, Denmark, Germany and Luxembourg with a HQ in Berlin.  
ABOUT THE TEAM
The AI Team advances intelligent automation through UnzerAI, our internal platform that helps employees, merchants, and partners discover and use information quickly and efficiently. By blending cutting-edge prompt engineering, vector search and fine-tuning, UnzerAI delivers accurate, context-aware responses with the performance, reliability, and compliance our business requires.

What your work will look like: 

• Design and implement scalable backend services and APIs that power document search, chat, and AI-driven workflows using microservices and REST
• Build and manage retrieval-augmented generation RAG pipelines, integrating vector databases such as Pinecone or Elasticsearch into our knowledge platform
• Integrate open-source and cloud-based language models into production, developing fine-tuning workflows on proprietary data to enhance relevance and reduce errors
• Own the full software development lifecycle, translate business requirements into design, write and test code, deploy using CI/CD and infrastructure as code, and monitor services in production
• Securely ingest and index internal knowledge bases such as Confluence, SharePoint, and document stores, implementing PII detection and redaction along with robust access controls

What you need to be successful in this role: 

• 5+ years of Python experience focused on building robust, performant backend systems
• Hands-on with LLM frameworks (Hugging Face Transformers, LangChain) and vector databases (Pinecone, FAISS), plus experience fine-tuning models on custom data
• Solid understanding of prompt engineering techniques and retrieval-augmented generation workflows
• Proven track record deploying and operating scalable, secure services on AWS or equivalent cloud platforms
• Expertise with containerization and orchestration (Docker, Kubernetes) and serverless architectures
• Familiarity with MLOps tooling for model training, deployment, and monitoring (MLflow, Kubeflow, or similar)
• Skilled in CI/CD pipelines using GitHub Actions, Jenkins, or comparable tools
• Strong analytical mindset, excellent communication skills, and a natural ownership mentality, thriving in collaborative, fast-paced environments

Please note that we will not sponsor your visa or relocation, and you must have a valid work permit to be eligible for this position.

What's next:

• Why You’ll Love Working with Us Joining the AI-Team means shaping the next generation of intelligent knowledge tools at a leading European payments technology provider. You’ll work with cutting-edge open-source and cloud-based models and be part of a supportive team that values innovation, security and real-world impact. 
• Does it sound exciting? -  Apply with your CV in English. Please don’t shy away if you don’t meet all the requirements! We’re looking forward to meeting you. 
• We will get back to you within 7 days from receiving your application.  
• The interview process includes a 30min intro call with a TA Partner, 90 min conversation with the technical team and a 45min call with your potential manager. Please note the process might alter depending on our team’s availability.  

What’s in there for you: 
🏡 Work from home up to 60% of the time. We want you to keep your work-life balance.  🚲 Mobility support, whether you choose a Bike or a Deutschland ticket - we've got you covered.  🫴 Explore counselling assistance, be it for professional or personal matters, through our associated platform.  💰 Pension scheme, we want to give back and help you secure your future.  🏖️ 15 days a year of workation from your desired destination within the EU.  🕟 Flexible working hours – you get to choose the schedule that works best for you!  📗  Learning budget of 1000 euros per year – you can develop your passions with us.  🎉  Enjoy some fun moments with your coworkers – we throw a company party once a year and host several team events!  
*Unzer is an equal employment opportunities workplace, and we commit to hiring regardless of race, sex, gender identification, sexual orientation, national origin, native language, religion, age, disability, marital status, citizenship, genetic information, pregnancy, or any other characteristic protected by law. Please refrain from including your picture and age with the application. #LI-HYBRID