Senior ML Data Scientist — Fraud Detection & Production

Extend; San Francisco (CA); Hybrid; USD 135,000 - 165,000; Full time

Benefits offered by this job

Stock options

Medical benefits

401(k) plan

Job summary

Extend is transforming post-purchase experiences in San Francisco with AI-driven solutions for fraud detection, returns, and protection. We seek a Senior ML Data Scientist to own cutting-edge models built on signals from hundreds of millions of users to protect customers and drive revenue.

You will lead the full data science lifecycle, partnering with Product, Engineering, and fraud teams to translate data into scalable, production-grade ML systems that stop bad actors and unlock business value.

Qualifications

• 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
• Candidates must be located within the continental United States

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

Skills

Python

SQL

ML fundamentals

Empathetic team player

Collaboration

Data-driven

Education

Bachelor's degree in Mathematics, Statistics, Computer Science, Engineering, OR Operations Research, Physics or related field

Tools

PyTorch

Scikit-learn

XGBoost

Job description

Extend is transforming post-purchase experiences in San Francisco with AI-driven solutions for fraud detection, returns, and protection. We seek a Senior ML Data Scientist to own cutting-edge models built on signals from hundreds of millions of users to protect customers and drive revenue.

You will lead the full data science lifecycle, partnering with Product, Engineering, and fraud teams to translate data into scalable, production-grade ML systems that stop bad actors and unlock business value.