Senior Machine Learning Engineer

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Machine Learning Engineer at Nubank

At Nubank, Machine Learning Engineers sit at the core of how we make decisions at scale. We build, train, and deploy models that drive credit, fraud, risk, personalization decisions and a growing set of AI-native experiences for millions of customers every day. We do it with engineering rigor, statistical depth, and a deep focus on impact.

Our MLEs work across the full modeling lifecycle: framing business problems as ML problems, engineering features, training and validating models, and deploying and monitoring them in production. We value small, independent teams that move fast, own their decisions end-to-end, and hold themselves to a high bar for quality and craft.

Increasingly, that work also includes Generative AI and Agentic Engineering. Depending on the problem, our engineers design and build systems that combine models, tools, workflows, evaluation loops, and human oversight to solve real business tasks reliably in production.

We strive for state-of-the-art ML practices that currently include a variety of technologies. While we value candidates that are familiar with them, we are also confident that engineers who are interested in joining Nubank will be able to learn from our team.

• Large-scale model training and experimentation pipelines
• Feature engineering and feature stores feeding both batch and real-time models
• Model deployment and serving in production, with monitoring through operational and business metrics
• Distributed data processing for training datasets at scale
• Continuous Integration and Deployment into AWS and Kubernetes
• Experiment tracking, model versioning, and reproducibility tooling
• A robust data platform built on modern ETL/ELT practices

As a Machine Learning Engineer, you’re expected to:

• Directly contribute to Nu Colombia’s strategy and performance mainly by building forecasting models and models to assess and decide on marketing investments
• Frame ambiguous business problems as well-defined modeling problems
• Design, build and validate machine learning models, ensuring statistical rigor and business relevance
• Engineer and maintain features and datasets used for training and inference
• Deploy and maintain ML models in both batch and real-time scenarios, integrating them with other systems and monitoring through operational and business metrics
• Lead modeling projects end-to-end — from problem framing and stakeholder alignment to delivery, monitoring and iteration
• Translate business needs into modeling strategies aligned with Nubank's architecture and long-term goals

What We're Looking For

• Strong foundation in statistics, machine learning theory and modeling techniques (e.g. regression, tree-based models, deep learning)
• Programming experience in Python and familiarity with ML libraries (e.g. scikit-learn, PyTorch, TensorFlow, XGBoost)
• Experience training, validating, and tuning models, with solid understanding of overfitting, bias-variance tradeoff and evaluation metrics
• Understanding of the ML model lifecycle, from training and evaluation to deployment and monitoring
• Ability to write efficient SQL queries and work with analytical data environments
• Strong communication skills to collaborate with both technical and business stakeholders
• Passion for building high-quality, production-grade models

Nice to Have

• Experience with cloud platforms such as AWS, GCP or Azure
• Familiarity with distributed systems, microservices and asynchronous architectures
• Experience with feature stores, MLOps tooling and experiment tracking (e.g. MLflow, Feast, Airflow)
• Knowledge of data architecture patterns (Data Lake, Data Warehouse, Data Mart)
• Experience with data visualization tools (Looker, Power BI, Tableau or similar)
• Knowledge of software engineering best practices: testing, clean code, documentation

Core Benefits

• Chance of earning equity at Nu
• Extended maternity and paternity leaves
• Health and life insurance
• NuCare - Our mental health and wellness assistance program
• Nucleo - Our learning platform of courses
• NuLanguage - Our language learning program
• Vacations of 15 workdays
• Gym partnership
• Work-from-home Allowance
• Parental Consultancy
• Relocation Assistance Package, if applicable

Work Model

Hybrid 2-3 times/week: Our hybrid work model brings us to the office at least twice a week, on strategic days designed to maximize team connection and collaboration.
For more details, visit https://building.nubank.com/nu-hybrid-work-model/

Role Location

Bogota, Colombia.