Senior Data Scientist Job at Adevinta (Barcelona)

Senior Data Scientist

Adevinta

Location:
Spain , Barcelona

Category:
IT - Software Development

Contract Type:
Not provided

Salary:

Not provided

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Job Description:

We are looking for a Senior Data Scientist to join our mission to make our platform an even safer place to trade. You will be responsible for designing, building, and continuously enhancing production-grade, end-to-end machine learning models that detect fraud and assess user risk in the Trust and Safety domain. You will be part of a cross-functional business area composed of multiple teams including experts from Product, Customer Service, Analytics, Data and Engineering. Together, you’ll tackle one of the most meaningful challenges in online platforms: building trust at scale. This is your opportunity to improve the experience of millions of users and have an impact by building a platform that enables sustainable trade for everyone.

Job Responsibility:

Understand fraud patterns, user trust needs and identify where Machine Learning can bring the greatest impact
Train and evaluation of ML models from scratch or fine-tune existing ones for fraud detection and behavioural analytics
Work as part of an agile cross-functional development team with a “win together, lose together” mindset, having end-to-end responsibility from design and development to deployment, monitoring, and maintenance in production
Engineer and select features from large, complex datasets to improve model accuracy and robustness
Monitor and evaluate ML models in production, conduct model experiments, comparing variants and identifying improvement and retraining needs
Ensure data and model quality, integrity, and reproducibility in production environments
Share your knowledge, evolve best practices with your colleagues to boost machine learning at Kleinanzeigen strengthening our ML community
Proactively identify opportunities to apply ML for fraud detection and increased user trust
Promote ethical AI use, ensuring fairness, transparency, and accountability in all models developed
Proactive collaboration with data and application engineers to shape data models and ensure ML-readiness for production

Requirements:

Master’s degree in computer science, data science, statistics, mathematics or related field (or equivalent experience)
At least 5+ years of proven experience applying ML methods to build and deploy production-grade models (e.g., XGBoost, Random Forests, Logistic Regression, Neural Networks, Transformers)
Strong proficiency in Python and ML libraries (e.g., scikit-learn, PyTorch, XGBoost), with proven experience applying classical ML to structured and time series data, including feature engineering, model evaluation (e.g., precision/recall, AUC), and deploying scalable models (e.g., XGBoost, Random Forests, Logistic Regression) to production
Solid understanding of ML/DS best practices, including model validation, A/B testing, feature engineering, and pipeline management ensuring quality and robustness of data science outputs
Practical experience with Large Language Models (LLMs) for tasks such as classification, summarization, or risk signal extraction from unstructured text, with a clear understanding of evaluation and ethical considerations in production use
True team player mentality, with excellent communication skills including ability to explain complex ML results to non-technical stakeholders

Nice to have:

Knowledge and experience with fraud detection or Trust & Safety domain
Familiarity with cloud-based environments (e.g., AWS) and production ML tools (e.g., SageMaker, Airflow, MLflow)
Experience working in Agile teams with modern DevOps/dataops practices
Awareness of ethical and regulatory concerns in AI systems

What we offer:

An attractive Base Salary
Participation in our Short Term Incentive plan (annual bonus)
Work From Anywhere: Enjoy up to 20 days a year of working from anywhere
A 24/7 Employee Assistance Program for you and your family
A collaborative environment with an opportunity to explore your potential and grow
A range of locally relevant benefits

Additional Information:

Job Posted:
February 04, 2026

Employment Type:

Fulltime

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