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

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