Senior Machine Learning Engineer

Affirm is a financial technology company that provides transparent, no-hidden-fee payment plans. The ML Fraud team builds and improves machine learning systems that make real-time transaction decisions, protecting consumers and merchants while balancing fraud loss, customer experience, and conversion.

• Lead development of new fraud prediction models using a mix of approaches for tabular, graph, and behavioral data.
• Build and scale feature pipelines and training datasets from proprietary and third-party signals.
• Prototype new modeling ideas, run offline experiments, and drive best-performing approaches into production with risk controls.
• Productionize models into batch and/or real-time decision systems, improving reliability, latency, and operational robustness.
• Instrument and monitor model and data health, and define retraining/backtesting workflows.
• Identify and implement foundational improvements to team model-building processes.
• Collaborate across Engineering, Fraud Analytics, Product, and ML Platform to define requirements and communicate results.

• 6+ years experience researching, training, tuning, and launching ML models at scale (PhD can count for up to 2 years).
• Track record of delivering high-impact ML models in a low-latency live setting.
• Strong Python skills and production-quality code.
• Experience with tabular classification models (gradient-boosted decision trees like LightGBM/XGBoost/CatBoost).
• Experience with a deep learning framework (PyTorch preferred).
• Experience with distributed data processing (Spark preferred; Ray/Dask or similar).
• Experience with ML lifecycle tooling (Kubeflow, Airflow, MLflow, or equivalent).
• Proficient in AI-powered developer tools (e.g., Claude Code, Cursor).
• Comfortable navigating large codebases, debugging, and providing code reviews.
• Strong communication skills for global collaboration.

Base pay range: $153,000 - $213,000 CAD per year. Total compensation may include monthly stipends for health, wellness, and tech spending, and benefits including 100% subsidized medical, dental, and vision coverage for employees and dependents. Eligible for equity rewards. Benefits also include flexible time off, generous holiday calendars, and an employee stock purchase plan (ESPP).

Remote Canada, open only to candidates residing in Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, or Saskatchewan.