Senior Machine Learning Data Scientist

About the role

The Fraud & Machine Learning team is the secret sauce behind Extend’s post-purchase protection platform. As a Senior ML Data Scientist, you will own the development of cutting-edge machine learning models based on signals and transactions from hundreds of millions of users to detect and prevent fraud, assess risk, and unlock business value.

Responsibilities

• Own the model lifecycle: requirements, experimentation, model development, evaluation, and model cards, partnering with ML engineers on deployment and production infrastructure
• Translate complex fraud patterns into well-framed ML solutions: defining what to model, what success looks like, and where ML adds value vs. simpler approaches
• Design and maintain feature engineering pipelines for model development
• Monitor model quality in production, tracking performance over time, detecting data drift, and determining when to retrain
• Partner closely with leadership, go-to-market, fraud operations, product, and engineering teams to define and execute effective fraud strategies
• Champion a culture of continuous learning, experimentation, and collaboration across the fraud and broader data science teams

Requirements

• Hands-on, proactive, and analytical professionals who are passionate about using data to solve complex, real-world problems
• Bachelor’s degree or higher in a quantitative field such as Mathematics, Statistics, Computer Science, Engineering, Operations Research, Physics or related field
• 3+ years of work experience building and deploying machine learning systems into production
• Strong proficiency in Python and SQL
• Strong understanding of ML fundamentals: model selection, evaluation methodology, feature engineering, and common failure modes
• Hands-on experience with PyTorch, scikit-learn, and XGBoost (or similar gradient boosting frameworks)
• High attention to detail, strong intellectual curiosity, and a deep understanding of user behavior and fraud patterns
• Empathetic, humble, and collaborative team player

Qualifications

• Candidates must be located within the continental United States

Preferred

• Experience building fraud detection or risk assessment systems
• Experience with cloud ML platforms, particularly AWS (e.g., SageMaker)
• Experience with graph data and graph-based models (e.g., PyTorch Geometric)
• Experience with model monitoring and observability tooling (e.g., Arize)

Benefits

Life at Extend includes:

• Working with a great team from diverse backgrounds in a collaborative and supportive environment
• Competitive salary based on experience, with full medical and dental & vision benefits
• Stock in an early-stage startup growing quickly
• Generous, flexible paid time off policy
• 401(k) with Financial Guidance from Morgan Stanley

Pay

Estimated Pay Range: $135,000 - $165,000 per year salaried*

* The target base salary range for this position is listed above. Individual salaries are determined based on a number of factors including, but not limited to, job-related knowledge, skills and experience.