Principal ML Engineer

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Split Pay, a Series B fintech, is seeking a Principal Machine Learning Engineer to lead ML initiatives across underwriting, fraud prevention, payment optimization, and marketing efficiency. This role involves setting technical direction, building and deploying ML models, and mentoring engineers. The position is based in Lisbon, Portugal, and offers a competitive salary with equity.

• Set the technical direction for machine learning across Split Pay.
• Own the full lifecycle of ML systems from problem formulation to deployment and monitoring.
• Build and improve models for underwriting, credit risk, fraud detection, payment routing, collections, and marketing optimization.
• Combine traditional statistical/ML techniques with foundation models and LLM-based approaches.
• Work directly on the underwriting stack and mentor engineers.

• Exceptional depth in machine learning with substantial experience building and operating ML systems in production.
• Experience with both traditional ML (ranking, classification, tree-based models, calibration) and modern deep learning/LLM systems.
• Strong Python and SQL skills.
• Experience designing scalable training, inference, and model-monitoring infrastructure in a cloud environment.