End-to-end Archives - Building Nubank

Software Engineering October 19, 2026

The code was the easy part: Lessons from contributing to the Clojure language

What two Clojure core contributions taught me about debugging, compatibility, and making technical reasoning understandable to others.

AI Research October 15, 2026

Squeezing ~2× MFU out of our training runs

How attention-kernel selection, compiler integration, and optimizer implementation shape Transformer model training speed

Data science & Machine Learning October 14, 2026

Feature stores in real-time ML, part 3: Examples from Nubank

Written by: Felipe Almeida, with contributions from Luiz Felix, Vívian Miranda, Lucas Nolasco, and Caroline Custodio. This is part 3 of a 3-part series on Feature Stores for Real-time ML. View part 1 and part 2. Quick recap and introduction In part 1 of this series we described what feature stores are and why they […]

Data science & Machine Learning September 28, 2026

Beyond A/B Testing: Designing Experiments When the Space Is Too Large to Explore

A practical guide to D-optimal designs, Fedorov's algorithm, and how business restrictions shape what we can test and estimate

Data science & Machine Learning September 17, 2026

When the team plays, Pix pauses: what the World Cup teaches us about outliers

How World Cup matches turn everyday payment patterns into outliers and what those anomalies can teach us about data, risk, and reliability

Life at Nu September 16, 2026

Designing Claude for ears, not eyes: An accessibility skill for blind and low-vision users

How a cognitively diverse IT team at Nubank, they coded screen reader-friendly rules into Claude's instructions, treating auditory comprehension as an engineering constraint

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