Detect fraud in milliseconds, at the moment a transaction happens, without blocking legitimate customers. Machine Learning Engineer - Spain Madrid or Barcelona, Spain · Permanent · Hybrid What you'd actually work on Building and maintaining fraud detection and risk-scoring models used on live transactions Developing features from transactional, behavioural, account, and device data Training and evaluating models against new and evolving fraud patterns Deploying models into low-latency production systems Reducing false positives while maintaining effective fraud detection rates Working with risk specialists to translate fraud scenarios and business rules into model features Designing feedback loops using confirmed fraud cases, manual reviews, and transaction outcomes Monitoring model performance, feature quality, drift, latency, and prediction distributions Investigating model degradation and changes in customer or fraud behaviour Improving model deployment, versioning, retraining, and rollback processes Documenting model behaviour and decisions for engineers, risk teams,



and auditors Contributing to code reviews, automated testing, CI/CD, and ML engineering standards Where it gets technically interesting Real-time inference under strict latency constraints, with decisions required before transactions are completed Highly imbalanced datasets where confirmed fraud represents only a small proportion of all transactions Fraud patterns that change deliberately in response to existing detection methods Managing delayed or incomplete labels when transaction outcomes are not immediately known Balancing fraud detection rates against the commercial and customer impact of false positives Identifying drift in models and features before it results in significant financial losses Combining machine learning outputs with business rules and manual risk controls Meeting explainability and traceability requirements for decisions that may need to be reviewed later Rolling out new model

📌 Machine Learning Engineer (Madrid)
🏢 The French Sourcer
📍 Madrid