Lead ML Data Engineer, AI Core

About the role

Nu is a digital financial platform serving over 127 million customers in Brazil, Mexico, and Colombia. We combine technology, data intelligence, and efficiency to offer simple, accessible, and human financial products.

Key Responsibilities

• Design and build scalable data ingestion pipelines for our AI Core platform.
• Implement data quality monitoring and validation systems to ensure reliable data flow.
• Model new types of data into our foundation models.
• Analyze the impact of new data sources on existing models and conduct experiments to measure performance improvements.
• Develop and maintain data preparation workflows for model training using distributed computing frameworks like Ray.
• Tune and optimize machine learning models when new datasets are integrated.
• Collaborate with AI Core ML, Platform, and Infra teams to ensure seamless data flow across our ML infrastructure.
• Lead technical initiatives to improve data engineering practices and set standards for data quality, pipeline reliability, and model-data integration.
• Mentor team members and contribute to hiring activities, fostering a diverse and innovative team.

Basic Qualifications

• Typically 6+ years of experience in machine learning engineering, data engineering, or related fields.
• Proven experience designing and building data ingestion pipelines at scale, with expertise in distributed computing frameworks.
• Strong background in applied machine learning, including model training, hyperparameter tuning, and performance evaluation.
• Experience analyzing how data changes impact model performance and designing and running experiments to measure improvements.
• Proficiency in Python for data engineering and ML workflows, with experience working with large-scale data processing systems.
• Solid understanding of data quality principles and experience implementing monitoring, validation, and alerting systems.
• Strong problem-solving skills with the ability to address complex, ambiguous problems requiring coordination across multiple teams.
• Excellent communication skills, capable of explaining technical concepts to both technical and non-technical stakeholders.
• Demonstrated leadership experience, including mentoring team members and contributing to technical decision-making.

Preferred Qualifications

• Experience with MLflow or similar model tracking and versioning systems.
• Knowledge of foundation models, fine-tuning workflows, and transformer architectures.
• Experience with data pipeline orchestration tools (Dagster, Airflow, or similar).
• Background in financial services or fintech, understanding the unique data challenges in this domain.
• Experience working in a fast-paced, high-growth environment with distributed teams.
• Track record of reducing complexity in data systems and improving developer experience for ML teams.

Benefits

• Opportunity of earning equity at Nu
• Medical Insurance
• Dental and Vision Insurance
• Life Insurance and AD&D
• Extended maternity and paternity leaves
• Nucleo - Our learning platform of courses
• NuLanguage - Our language learning program
• NuCare - Our mental health and wellness assistance program
• 401K
• Saving Plans - Health Saving Account and Flexible Spending Account
• Work-from-home Allowance
• Relocation Assistance Package, if applicable.

Work Model for this Role

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.