Machine Learning Engineer, Fraud

Join the Future of Commerce with Whatnot!

Whatnot is the largest live shopping platform in North America and Europe to buy, sell, and discover the things you love. We're re-defining e-commerce by blending community, shopping, and entertainment into a community just for you. With hubs in the US, UK, Germany, Ireland, Poland, and Australia, we're building the future of online marketplaces together.

From fashion, beauty, and electronics to collectibles like trading cards, comic books, and even live plants, our live auctions have something for everyone.

And we're just getting started! As one of the fastest growing marketplaces, we're looking for bold, forward-thinking problem solvers across all functional areas. Check out the latest Whatnot updates on our news and engineering blogs and join us as we enable anyone to turn their passion into a business, and bring people together through commerce.

Role

• Design, train, and deploy both traditional ML and LLM-powered models to detect fraudulent behaviors across users, payments, and marketplace interactions.
• Lead the end-to-end architecture of fraud detection, prevention, and intervention systems balancing platform security with a seamless user experience.
• Build intelligent user graphs to model behavioral patterns, collusion networks, and account connectivity.
• Develop scalable data pipelines and real-time inference systems supporting high-volume, low-latency ML workloads.
• Conduct deep behavioral and adversarial data analysis to uncover fraud trends and continuously improve detection accuracy.
• Partner cross-functionally with Trust & Safety, Payments, and Infrastructure teams to develop features, labels, and model evaluation pipelines.
• Implement model monitoring and drift detection systems to ensure reliability and responsiveness.
• Contribute to fraud risk orchestration, combining rules, models, and heuristics for decision automation.
• Define and track key metrics and dashboards for fraud detection effectiveness (e.g., precision, recall, false-positive rate, latency).
• Stay ahead of emerging fraud tactics and continuously translate insights into adaptive, production-ready systems.

We offer flexibility to work from home or from one of our global office hubs, and we value in-person time for planning, problem-solving, and connection. Team members in this role must live within commuting distance of our SF, NYC, LA OR SEA hubs.

You

Curious about who thrives at Whatnot? We've found that embodying a low ego, growth mindset, and high-impact drive goes a long way here.

Compensation

For US-based applicants : $245,000 - $345,000 / year + benefits + stock options

The salary range may be inclusive of several levels that would be applicable to the position. Final salary will be based on a number of factors including, level, relevant prior experience, skills and expertise. This range is only inclusive of base salary, not benefits (more details below) or equity in the form of stock options. Benefits

Home office setup allowance

Monthly allowance for wellness

All Whatnauts are expected to develop a deep understanding of our product. We're passionate about building the best user experience, and all employees are expected to use Whatnot as both a buyer and a seller as part of their job (our dogfooding budget makes this fun and easy!).

16 weeks of paid parental leave + one month gradual return to work

EOE

Whatnot is proud to be an Equal Opportunity Employer. We value diversity, and we do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, parental status, disability status, or any other status protected by local law. We believe that our work is better and our company culture is improved when we encourage, support, and respect the different skills and experiences represented within our workforce.