Machine Learning Engineer (AI CORE)

Nubank•Palo Alto, CA

2d•Onsite

About The Position

About Us Nu is one of the largest digital financial platforms in the world, with more than 122 million customers across Brazil, Mexico, and Colombia. Guided by our mission to fight complexity and empower people, we are redefining financial services in Latin America and this is still just the beginning of the purple future we're building. Listed on the New York Stock Exchange (NYSE: NU), we combine proprietary technology, data intelligence, and an efficient operating model to deliver financial products that are simple, accessible, and human. Our impact has been recognized by global rankings such as Time 100 Companies, Fast Company’s Most Innovative Companies, and Forbes World’s Best Bank. Visit our institutional page https://international.nubank.com.br/careers/ About the role At AI Core, we are scaling the impact of our AI initiatives to become the primary driver of Nubank’s most critical decision systems. We are seeking Machine Learning Engineers to lead high-impact research projects that bridge the gap between state-of-the-art AI and production-grade financial systems. You will be responsible for solving complex, ambiguous problems using Deep Learning and Foundation Models, ensuring our architectures are scalable, efficient, and driving measurable business results.

Requirements

Professional Experience: 5-7+ years in applied AI/ML, with a proven track record of delivering research-driven systems into production environments
Technical Mastery: Deep expertise in Deep Learning architectures (Transformers, Multimodal, or GNNs). Strong coding skills in Python and proficiency with frameworks like PyTorch, JAX, or TensorFlow . Solid understanding of MLOps and the constraints of deploying models at scale.
Problem Solving: Sophisticated skills in ML problem formulation and the ability to navigate uncertainty when data is messy or unavailable.
Communication: Ability to communicate complex technical concepts to both technical peers and cross-functional stakeholders, ensuring alignment and buy-in.
Analytical Capacity: Experience with large-scale experimentation and A/B testing to validate research hypotheses.

Responsibilities

Research Execution & Technical Leadership (Complexity & Autonomy) Lead and execute complex applied research initiatives independently, focusing on building and optimizing architectures (e.g., Transformers, GNNs) that can be deployed across critical use cases like Credit, RecSys, GenAI, and real-time inference.
Address difficult and ambiguous modeling problems that require coordination across various stakeholders (Data, Infra, Product), delivering innovative solutions with a clear focus on medium-term impact.
Bridge the gap between research and production by designing architectures that respect MLOps constraints, ensuring models are optimized for latency, interpretability, and cost-efficiency.
Strategic Impact & Collaboration (Impact) Develop and deliver innovative solutions that address project-level challenges, focusing on pushing the latest platform and AI research improvements into downstream production models.
Actively participate in cross-functional collaborations , ensuring that research outputs are seamlessly integrated into Nubank's decision-making engines.
Establish technical standards within the AI Core team for experimentation, model evaluation, and code quality, inspiring peers to raise their performance.
Mentorship & Function Contribution (Function Contribution) Serve as a technical mentor for senior engineers and researchers, providing guidance on deep learning fundamentals, problem formulation, and research methodology.
Actively contribute to the function's growth by participating in mandatory activities like hiring (interview panels) and leading internal task forces to improve our ML lifecycle.
Contribute to thought leadership by participating in research collaborations or internal papers that align with Nubank’s strategic goals.