Senior Data Scientist - Fraud Model Validation at Klarna | GB | Rezi

Senior Data Scientist - Fraud Model Validation at Klarna

Senior Data Scientist - Fraud Model Validation

Klarna · GB

1 weeks ago

Senior Data Scientist - Fraud Model Validation

Klarna · GB

9 days ago
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About the Role

First-line fraud teams at Klarna build models against real-time attacks on payments, logins, and identity. This role involves independently reproducing results, building challenger models, and stress-testing assumptions from data pipeline to production deployment. It is a second-line position reviewing methodologies built with scikit-learn, LightGBM, graph models, anomaly detection, and GenAI-based components. You will also build tooling, such as agentic AI systems, to automate risk surfacing and ensure validation keeps pace with development.

Responsibilities

  • Assess model performance using fraud-specific metrics and weigh each against its real business trade-off.
  • Review transaction datasets exceeding 100 million records and feature pipelines with hundreds of features for representativeness, leakage risk, and bias.
  • Evaluate drift detection, retraining strategies, and production monitoring practices to confirm they catch degradation before it costs the business.
  • Assess CI/CD and deployment controls in Docker, Jenkins, and AWS SageMaker, S3, Athena, and Lambda environments.
  • Evaluate model governance documentation, explainability approaches, and compliance with regulatory expectations on model risk, fairness, and data privacy.
  • Validate emerging techniques as first-line teams adopt them, including graph networks, behavioral biometrics, anomaly detection, and GenAI-based systems.
  • Document validation outcomes and communicate model risks directly to first-line data scientists, ML engineers, and business stakeholders.

Requirements

  • 3+ years hands-on experience in fraud-related modeling (transaction fraud, account takeover, identity fraud, or payments fraud).
  • Proficiency in challenging implementations of tree-based models (e.g., LightGBM), anomaly detection techniques, and graph or network models.
  • Experience across the full ML lifecycle, from feature engineering through production deployment and monitoring.
  • Fluency in Python and SQL.
  • Experience using PySpark or Spark to process data at scale.
  • Experience building agentic AI workflows, designing automation rather than just using off-the-shelf tools.
  • Understanding of model validation principles and model risk governance, including assessing bias, fairness, explainability, and privacy risk.
  • Ability to deconstruct complex models, explain flaws, and communicate findings to both technical teams and non-technical senior stakeholders.

Skills

  • scikit-learn
  • LightGBM
  • graph models
  • anomaly detection
  • GenAI
  • Docker
  • Jenkins
  • AWS
  • Python
  • SQL
  • PySpark
  • Spark
  • agentic AI

Location

  • 26 countries

Work Type

  • Co-located teams
  • Office 2-3 days per week

Experience Level

  • 3+ years

Education Level

  • Advanced degree (Master's or PhD) in a quantitative field (data science, statistics, mathematics, computer science, physics, or engineering) - Bonus

About the Company

  • Klarna is building an everyday finance network, helping over 120 million consumers across 26 countries save time and money, and worry less about their finances.
  • Working here means taking on problems most companies never get to solve and being hands-on with technology.
  • Non-obvious backgrounds are welcome.
  • Diversity of skills, perspectives, and backgrounds is how we create, innovate, and disrupt.