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How we built a cache that’s never stale

This article has been migrated to our new blog. Find it at https://building.nubank.com.br/the-evergreen-cache/

Photo by Samuel Scrimshaw on Unsplash

NuConta is Nubank’s digital bank account. It’s built using the same amazing stack that powers our other products: Clojure, Datomic, and Kafka; all deployed to AWS cloud. At the team building NuConta, we’re also big fans of event sourcing.

Event sourcing is a fancy expression for an idea that’s simple at its core: instead of storing the current state of the system in a database, store each step of the story so far. …


This article has been migrated to our new blog. Find it at https://building.nubank.com.br/tech-perspectives-behind-nubanks-first-acquisition-deal/

What this business move means and how it strengthens our scaling capacity

2019 was an outstanding year for Nubank. 2020 kicks in bearing the exciting challenge of scalability and sustainable growth to new geographies, new segments, and new products while nurturing our unique customer excellence. Achieving those goals is deeply connected to the way we are organized as a company and the diverse people and capabilities we have inside our teams — which is why we are so excited to share some news that will help us…


Here’s everything you need to know about the role that DS plays at Nubank and how to join our team

This article has been migrated to our new blog. Find it at https://building.nubank.com.br/hiring-for-data-science-at-nubank/

Nubank was created to fight the complexity of the financial system and empower people. We use Technology, Design, and Data Science to develop amazing products and services that help customers regain control over their finances.

As a fintech, having very diligent processes backed up by data-informed decision making is crucial to our operations, meaning we can offer the right set of products to the right customer at…


This article has been migrated to our new blog. Find it at https://building.nubank.com.br/introducing-fklearn-nubanks-machine-learning-library-part-ii/

Read Part I of this series here.

In the first part of this series, we talked about fklearn’s principles, and how it can be useful to build machine learning pipelines using pure functions. However, the biggest benefits of using fklearn come when doing analysis and validation of models, as we’ll see next.

Extensible Validation

For models that go into production, validation often requires a lot more than just finding out the value of some metric on a holdout set, or comparing a metric to a benchmark. …


A quick view on why we chose this technology and how we use it to fight complexity and empower people

This article has been migrated to our new blog. Find it at https://building.nubank.com.br/working-with-clojure-at-nubank/

Nubank has helped change the landscape of financial services in Brazil. We launched our first product in 2014, a no-fee credit card, and since then we grew to be the most innovative company in Latin America and the biggest independent digital bank in the world, with more than 15 million customers.

Our portfolio of products includes, other than the credit card, NuConta, a digital savings account; Nubank…


From application to onboarding, here’s everything you need to know to join our engineering team.

This article has been migrated to our new blog. Find it at https://building.nubank.com.br/what-is-the-interview-process-like-for-software-engineers-at-nubank/

Nubank was born to fight complexity and empower people. We use technology, design and data science to create amazing products and services that give back to customers control over their finances — and combine that with outstanding customer support which is both human and efficient.

Man sitting on a chair smiling while working on a laptop and using headphones
Man sitting on a chair smiling while working on a laptop and using headphones
Rodrigo Gaião — Senior Tech Recruiter at Nubank

As Software Engineers play a big role in our company, we are constantly looking for talents to join our team — and, as everything we do at…


This article has been migrated to our new blog. Find it at https://building.nubank.com.br/how-we-do-on-call-rotations-at-nubank/

Here at Nubank, system stability is a core part of our business. However, as diligent as we are, sometimes things go awry. When that happens, it is paramount that our engineering team is ready to respond.

What is on-call?

On-call is the act of an engineer being available to respond immediately to service malfunction, at any time, any day of the year. It usually entails some sort of automatic alerting system, paired with a way to notify the engineer.

For the scope of this article, let us define an Alert…


An overview of the criteria and study we conducted to decide to use Flutter as our main technology for cross-platform mobile development.

by Alexandre Freire & Vinicius Andrade [disponível em Português]

This article has been migrated to our new blog. Find it at https://building.nubank.com.br/why-we-think-flutter-will-help-us-scale-mobile-development-at-nubank/

Nubank has been a mobile-first Fintech from the beginning. We started our mobile development with native apps for our Credit Card supporting both Android and iOS platforms back in 2013 and quickly adopted Kotlin and Swift after they were announced. For a while, we supported the Windows Phone platform.

As the company grew (we’re now the…


This article has been migrated to our new blog. Find it at https://building.nubank.com.br/products-are-never-really-done/

Pieces of paper containing wireframes and notes scattered on a desk; a person holding a pen.
Pieces of paper containing wireframes and notes scattered on a desk; a person holding a pen.

At Nubank, we want to deliver the best possible products to our customers. Period. This aspiration guides our product, engineering and design decisions from the moment we conceive of an idea to the first version of a product we put in a user’s hands to the endless iterations we make thereafter.

But what does “best possible product” really mean? How do we decide what features ultimately make it into a product, and when? How do we determine a product is ready for testing with real customers?

As…


This article has been migrated to our new blog. Find it at https://building.nubank.com.br/microservices-at-nubank-an-overview/

Microservices is the prevalent architectural style of the day. So much so that there isn’t much value in describing what it means and its advantages, there is plenty of great content available out there. Instead, we are going to talk a bit about what we’ve learned growing a complex system over the past six years.

The beginning

Six years is also the entire lifespan of the company, which means we started with microservices from day one, defying the standard advice of starting with a monolith. The rationale usually given…

Building Nubank

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