Senior Machine Learning Engineer (m/w/d)

Senior Backend Engineer

Permanent employee, Full-time · Berlin, hybrid

THE IMPACT YOU WILL MAKE

Help shape the future of conversational AI at charles by building the infrastructure behind Europe’s first brand-safe AI solution for WhatsApp. Our AI Agents - like Recco and Sue Port - are already live for customers, delivering real results, and scaling up rapidly to meet growing demand.

As a Senior ML Engineer, you’ll design and optimize the machine learning systems powering these agents, from recommendation engines to natural language understanding. You’ll play a key role in scaling our AI infrastructure and driving innovation as we expand the capabilities of our agents to transform how brands connect with their customers. Join us to tackle complex challenges and create cutting-edge solutions in a fast-growing, high-impact environment.

THIS IS WHAT YOU WILL BE DOING

• Architect services built for enterprise scale
• Tackle multilingual, conversation-driven e-commerce challenges
• Own end-to-end responsibility for production systems
• Run LLM operations at enterprise scale
• Optimize LLM inference for real-time workloads
• Develop and manage vector-search & embedding pipelines
• Work with a cutting-edge infrastructure stack

YOU’LL FIT GREAT WITH THESE SKILLS AND VALUES

• Advanced degree (Master’s or PhD) in Computer Science, Machine Learning, AI, Mathematics, Statistics, or a closely related discipline.
• Three to five years of hands-on experience in AI/ML engineering or data science, with a proven track record of shipping and integrating models in production.
• Expertise with large language models, retrieval-augmented generation, and model-evaluation techniques; strong command of Python and frameworks such as PyTorch, PyTorch-lightning.
• Practical familiarity with the AI/ML toolkits offered by major cloud providers (AWS, Azure, GCP).
• Sharp diagnostic skills for issues like model drift, data-quality anomalies, and performance bottlenecks, plus the ability to optimise end-to-end pipelines.
• Working knowledge of LLMOps/MLOps best practices and tooling for deployment, monitoring, and CI/CD automation.
• Genuine passion for cutting-edge AI/ML and a drive to create solutions that deliver tangible impact for users.

Meeting all requirements is not necessary to apply. We encourage candidates who meet some but not all of these qualifications to submit their application.

THINGS WE OFFER

• Working on challenging and impactful projects at the forefront of one of the most innovative industries in Europe
• Collaborating with some of the leading experts in Conversational Commerce and disrupting a fast-growing industry
• Joining forces with a unique community of Tech, Product, Sales, Success, and Marketing experts committed to building the best product in Conversational Commerce
• Having high visibility and impact across the business with the option to own and drive new initiatives
• Working with Weaviate, Gemini, and PyTorch
• Celebrating our major and micro-wins as well as getting to know each other better at regular team-building events
• Sharing VSOP (virtual stock options) in the ownership and success of charles
• Working in a vibrant office in the heart of Berlin overlooking the Wall memorial
• Earning a competitive compensation package

What else we offer?

• Urban Sports Club membership
• A weekly personal trainer
• Free company lunch on Thursdays
• A friendly, open, multicultural work environment
• Dog-friendly office in the heart of Berlin
• Discounts on BVG tickets

About us

charles is a SaaS startup that enables brand to build personal relationships with customers. With our software, businesses can chat with customers, send marketing campaigns, sell products, analyze results and automate processes. And we go beyond the tech to offer ongoing consultancy for future success. Our vision is to connect any kind of business with their customers via messaging apps to let them do what they need.

Founded by Kapten & Son co-founder, Artjem Weissbeck, and ex-McKinsey ecommerce lead, Andreas Tussing. charles is backed by Salesforce Ventures, Accel and HV Capital and has raised over EUR 30 million to build the global leader in conversational marketing SaaS for global consumer brands.

charles and diversity: be yourself and no-one else

Different perspectives bring innovation and richer work environments. We’re committed to building an inclusive company where you always feel like you belong, whatever your age, gender identity, ethnicity, religion, sexual orientation, disability, status or neurodiversity. These values sit at the heart of our hiring process, so we can create a welcoming workplace where everyone feels valued and heard.