Senior Data Scientist - Machine Learning

Posted 7/29/2026 · last confirmed live 8/26/2026

At Catawiki, every day brings the extraordinary! Whether it’s Daniel Ricciardo’s Formula 1 Car , a Woolly Mammoth’s Skeleton , Lady Gaga's Jumpsuit or Usain Bolt’s running shoe , we encounter exceptional objects every day. We’re a one-of-a-kind marketplace for buying and selling special objects. Each week, more than 100,000 unique items are auctioned, all carefully curated by our passionate in-house experts. Having sold over 25 million unique objects, our mission is to become the world’s most popular destination for special objects. As a growing, diverse and sustainable scale-up, we proudly live by three core values. If these values resonate with you, we’d love to explore how you can join us. Taking ownership and driving impact  Being open to change and feedback Being passionate about our mission and our customers.  Our Data Story With ten-thousands of active items on auction every day, hundred-thousands of bids, millions of users, and billions of events, the Catawiki platform generates vast amounts of data. We collect this data centrally, using it to generate business insights, as well as powering machine learning models that enhance our user experience, optimize our workflows, and keep our platform safe. We believe in creating flexible models that can be applied to a variety of use cases, and in experimentation and iteration to hit the ground running and continually improve the tools we build. The Data Team, which covers the full data spectrum of Machine Learning, Analysis and Data Engineering, has a clear a mission within Catawiki: Why : We believe that by using data in a smart way, we can build the best Catawiki possible. We want to have impact and see opportunities everywhere. How : We are builders, thinkers and talkers. We collaborate closely with every department to create value for our customers. We think big and hold ourselves to high standards, because our work really matters for the future of the company. What : As a result we create business value by delivering scalable, robust models and actionable insights and predictions. We help the company to find opportunities and understand success, and we empower everyone to use data to be successful. So what's the job As a Senior Machine Learning Data Scientist in the Data Team at Catawiki you will focus on delivering scalable and impactful data products. You’ll work closely with our product and development teams while implementing your work. This includes: Building production-ready models that apply machine learning and advanced data science techniques within our product offering by writing robust and scalable code. Finding data science opportunities by exploring our extensive mobile and web data, and applying machine learning and advanced statistics to tackle these real-world business problems. Being pragmatic when needed but also able to go deep into a problem, applying your expert knowledge of machine learning techniques Working with cross-disciplinary teams involving product owners, developers, UX designers, and business analysts in identifying improvements and new use cases for ML Deploy scalable models using Kubernetes on cloud infrastructure, producing real-time, asynchronous, and batch predictions Who you are  You are an all-around data scientist with 5+ years of experience who is as comfortable diving into the internals of a model implementation as discussing new opportunities for ML with product stakeholders Can use your broad skill set to solve challenging ML problems and have a high throughput. Are familiar with a range of different ML techniques and use that to select a good solution for their projects. Are able to considers the operating/deployment constraints of large models and implement solutions accordingly Give guidance and unblock others in your team by supporting them with advice and new techniques. Have a strong quantitative background (statistics, ML, sciences, etc.) Are fluent in Python and capable with SQL Have deployed ML models serving real time responses on a large scale Have demonstrable experience in building robust data products that created value for the company you worked for. The following are a plus: Proven ability to extract meaning from very big datasets with little engineering support. Experience with one or more of the following: PyTorch/Tensorflow, LightFM, Git, Docker, Kubernetes, Google BigQuery, MySQL, Spark, Airflow, Kafka, nginx, CI/CD,  An entrepreneurial mindset that enables you to get things done, even if that requires actions outside your own area or comfort zone. Where you'll be This role is based in Lisbon. We work in a hybrid model with two days a week in the office.  Why You'll Love Working with Us Create a visible impact by working at scale in a global organisation serving millions of customers across 80+ categories. In our flat structure, every role has a broad scope and directly impacts both our customers and the business. Learn and grow through our Learning & Development initiatives, including clear development plans and mentorship programmes to support your career progression. A culture of connection defines us . We’re a passionate, diverse team of 800+ Catawikians representing 60+ nationalities. We foster an inclusive and queer-friendly environment where everyone is encouraged to bring their full self to work. Celebrate life’s moments with us. You’ll receive a €100 Catavoucher when you join, a €50 Catavoucher on your birthday, and an extra day off each year to “Pursue Your Passion ” . We also offer additional leave for key work anniversaries and important life events. Benefits may vary by location. Our Offices and Way of Working Our vibrant offices in Amsterdam and Lisbon are designed to inspire collaboration. Most Catawikians operate in a hybrid setup, combining office-based and remote work, with a minimum of two days per week in the office, unless a role is explicitly stated as fully remote or fully office-based. Interested? Apply with an English CV and Cover Letter. By applying, you agree to Catawiki’s Applicant Privacy Policy. If you’re excited about this role but don’t meet every requirement, we still encourage you to apply anyway. 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This role is published by Catawiki on greenhouse. SwiftFit is not the employer and does not accept applications.