Machine learning engineer in fraud detection

Mangopay; Warszawa; On-site; PLN 260,000 - 380,000; Full time

Job summary

Mangopay is seeking a Senior Machine Learning Engineer to join our Data Science team. You will work on fraud prevention by developing end-to-end ML solutions from data sourcing to deployment and monitoring in production.

The role blends DS with ML engineering and data engineering, with a strong emphasis on reliability and security. You will build models to detect fraudulent payments, identity theft, and account takeovers, and you will lead projects that drive measurable impact for our products

Qualifications

• Minimum 5 years in Data Science or ML/DS field.
• Strong Python (pandas, NumPy, scikit-learn) and SQL skills.
• Experience deploying and maintaining ML models in production.
• Strong software engineering practices (clean code, tests, version control).
• Excellent English and Polish language skills.

Responsibilities

• Build and improve fraud detection solutions for payments and identity security.
• Lead end-to-end DS projects from data sourcing to production deployment.
• Develop data pipelines and datasets to support feature engineering and real-time inference.
• Develop and operate production ML services with reliability, scalability, and security.
• Create internal tools and workflow automations to improve efficiency.

Skills

Python

SQL

ML algorithms

Data analysis

Communication

English language

Polish language

Tools

AWS SageMaker

Kubernetes

Docker

CI/CD

Apache Kafka

Terraform

Snowflake

dbt

n8n

Job description

Описание

We are looking for a Senior Machine Learning Engineer to join our Data Science team and help develop and operate machine learning solutions for fraud prevention. This is a hands‑on, end‑to‑end role combining Data Science with Machine Learning Engineering and Data Engineering. You will work across the entire lifecycle of ML solutions, from sourcing and preparing data through model development to deployment and ongoing maintenance in production.

Задачи

Build and improve fraud detection solutions that help identify fraudulent payments, identity theft, and account takeover. Investigate fraud patterns by exploring transactional and behavioural data, identifying suspicious activity, and turning findings into actionable insights. Research new algorithms and data sources, and develop, evaluate, and maintain machine learning models that process millions of transactions. Build and maintain data pipelines and datasets supporting feature engineering, model training, and real‑time inference. Develop and operate production ML services, ensuring their reliability, scalability, performance, and security. Build internal tools and workflow automations to streamline processes and improve efficiency across the organization. Automation is close to our hearts! Lead end‑to‑end data science projects, from identifying business opportunities and designing solutions to delivering measurable impact on our products and clients' bottom line.

Требования

At least 5 years of professional experience in Data Science, applied Machine Learning, or a closely related field. Strong understanding of machine learning algorithms, statistics, feature engineering, model evaluation, and validation techniques. Excellent Python skills, including experience with the Python scientific stack: pandas, NumPy, and scikit‑learn. Strong SQL skills and experience working with large, complex datasets. Good software engineering practices, including clean code, testing, version control, and maintainability. Solid understanding of software architecture and design principles, with the ability to build maintainable and extensible solutions. Practical experience in at least one of the following areas: Machine Learning Engineering: deploying, monitoring, and maintaining ML models in production, with an understanding of ML lifecycle management and deployment practices. Practical experience in at least one of the following areas: Data Engineering: building and maintaining data pipelines, data transformations, and reliable datasets using modern data platforms. Willingness and ability to develop expertise in whichever of these two areas is less familiar to you. Strong analytical and problem‑solving skills, with the ability to independently navigate complex technical challenges. A pragmatic business mindset and excellent communication skills. Very good English and Polish language skills.

Будет плюсом

• Experience with AWS, particularly Amazon SageMaker
• Experience with Kubernetes, Docker, and CI/CD for deploying and operating production services
• Experience with Apache Kafka or other event streaming technologies
• Familiarity with Terraform or other Infrastructure as Code (IaC) tools
• Experience with Snowflake, dbt, or similar data transformation and warehouse technologies
• Experience building workflow automations with tools such as n8n
• Experience developing AI agents or applying generative AI to business problems
• A degree in mathematics, computer science, quantitative methods, econometrics, or engineering (not mandatory)
• Experience in fintech, banking risk, credit, or fraud detection

Условия

You will work on machine learning problems with direct business impact, taking ownership of solutions from initial exploration through production. This is an opportunity to combine Data Science with real‑world engineering, deepen your expertise in ML or Data Engineering, and help shape how our data and ML systems are developed and maintained. We value technical curiosity, initiative, pragmatic problem‑solving, collaboration, and continuous learning.