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Presentation: Scaling N26 Technology Through Hypergrowth

Track: Growing Unicorns in the EU: Building, Leading and Scaling Financial Tech Start Ups

Location: Whittle, 3rd flr.

Duration: 1:40pm - 2:30pm

Day of week: Wednesday

Slides: Download Slides

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What You’ll Learn

  1. Find out about the stages that N26 went through while hyper-growing.
  2. Learn about how technology choices can have an impact on the culture.


N26 is a mobile-first bank which was recently listed as the number one startup in Germany and one of the world's most valuable FinTechs. I joined the company 3 years ago, when it had less than 100 employees. Now there are over 1500 people working across 5 different locations. I will share my experience at N26, where I have led 3 different teams. A lot can happen in 3 years, especially during the time of hypergrowth. I will talk about the problems we (as engineers and tech leads) faced, the solutions that worked well and those which did not and how our technology adapted to demands of increasing scale and complexity.


What is the work you are doing today?


I'm a tech lead at N26. I've been working for the company for the last three years. N26 is a mobile challenger bank and we are divided into segments. The segment that I'm working on currently is the engagement segment. This means that we try to deal with features around engaging users with a useful app. These represent the home screen, which is like one of the heaviest screens of the application which everybody sees as soon as they log in.


What are the goals you have for the talk?


I've been working for the company for the last three years. For a start-up that looks like an eternity. At the very beginning, it was quite dynamic. Zero coordination in the sense like not formally expressed, but mostly informal. And you rely a lot on individual skills. And then we went through hyper-growth. this means that our engineering group grows like three or four times the initial size. So we went from having in something like 40 to 50 people to having 300.

There are a lot of really interesting challenges when you are scaling not only your infrastructure but also your teams, which is what I would like to talk about. Which situations came up while we were pushing for this growth? How do you achieve to get this growth? How do we distribute our teams? Which kind of concerns did we need to face while growing? Which things work well and which didn't really work or didn't scale that well while we were going through this kind of phase.


Can you tell me a bit about the technology stack at N26, what does that look like at a high level?


We use microservices architecture which means that potentially each microservice can have its own stack. But we tried to be consistent across our ecosystem. Which means that we started early on with Java because it's one of the most popular languages. But as we grow and discover new languages, we adopted Kotlin because of its simplicity and all that it brings to the table as a modern language. Currently, on our backend services, we only use Java and Kotlin and for most of our services we only use Kotlin. We use the spring boot for web frameworks and then for storage we rely mostly on SQL; for some others, we will use document-based storage. We use Rest for communication in between services, but we rely a lot on asynchronous communication using the AWS messaging systems.


Do you think those technology choices have an impact on the culture and your ability to scale the teams and keep your teams performing well?


Yeah, definitely. I think it's really important to pick the right technology stack for a couple of reasons. One of the things that you want to have with your stack is that it actually enables you to deliver faster because the end goal is that your users get more feature sets.

And then there are factors playing in there like, how many engineers can you hire for that stack? How many experienced people are there available in the market to grow your teams. Java is one of the most established languages, there is a huge pool of talent available to hire. But at the same time, Kotlin is a modern language. By including Kotlin, we can hire people from Java and then use them as well for Kotlin.

Microservices architecture was definitely one of the decisive decisions that we took because it really enables you to run parallel features, to organize your teams and to require less coordination between those teams.

And then the last one is to be able to grow dynamically. So this is what the cloud provides. We use AWS so we have 100 percent hosted in the cloud. And this really helps you to scale up or scale down depending on the situation. 


What do you want people to leave the talk with?


What is important about this talk is that people might be at different points of their journey as a company. The idea is that I am going to share what we did in the last three years, and in those three years we were small, we were medium, and we were like big, like right now. Each of those stages will have some learnings. Learnings may apply to the audience, and some others might not apply to the audience. There will be some main takeaways depending on where you are in your journey that you can apply to your day to day work.

Speaker: Folger Fonseca

Software Engineer and Tech Lead @N26

Folger is a Software Engineer and Tech Lead who has been working at N26 for the past 3 years. His main focus is mentoring team members, building backend microservices in cross-functional teams, designing systems, and engineering processes that perform at scale. In his free time, he enjoys volunteering for a non-profit organization where he teaches children how to code.

Find Folger Fonseca at

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