How Klarna geared up for peak season 2023

22 November 2023 - 1 min read


Alexander Carlsson

Communications lead for Klarna Engineering


Preparing for peak season of shopping is a continuously ongoing effort involving almost all of Klarna’s 300+ engineering teams. During Black Friday 2022, Klarna’s systems processed close to 6 million orders. That’s 4 million more than on an average day, peaking at 150 orders per second. Continue reading to hear directly from engineers on the Continuous Readiness team to learn more about preparations and improvements made for the 2023 Peak Season.

Of course, Black Friday is not just about the numbers. A successful shopping season is first and foremost about securing a safe and enjoyable experience for everyone using Klarna to score the best deals. With 62% of consumers expecting to do at least half of their holiday shopping online, there’s no room for errors.

 “Think of Peak Season like a big music festival” says Francesco Orlandi, Engineer on the Continuous Readiness team at Klarna. “Thousands of people are lining up to see their favorite artists. They expect their ticket to scan in a millisecond, world class entertainment on stage and definitely don’t want to waste time in a long line to get food. To be able to handle a big onrush like that, it’s crucial for the organizers to prepare everything down to the smallest detail ahead of time. The same is true on Black Friday.”

“People don’t have time for an app that keeps crashing or a checkout that takes too long to load. Klarna customers deserve a perfect experience every time”, highlights Michael Ståhle, Senior Engineer on the Continuous Readiness team at Klarna.




Raising the bar: Learnings for 2023
Thanks to the continuously ongoing preparations by hundreds of the company’s engineering teams, last year, Klarna encountered zero critical incidents during the week of Black Friday. We simultaneously decreased our daily cloud infrastructure costs by 50%. And while 2022 was a big success, it also gave us valuable insights into what we can do better. As part of that, we have continued to invest in the development of internal tools that can ensure a perfect shopping experience for shoppers and merchants.

So, how are we ensuring an enjoyable Black Friday for everyone using Klarna?

A reliable shopping experience — even during high traffic time periods.
Continuous performance testing is done to identify potential issues with a system, like slow response times, errors, or crashes. Think of it like a dress-rehearsal before a big play; costumes and stage properties set up exactly as they would be in a real performance, but without the risks of performing in front of a live audience.

For this year, Klarna has kept performance testing in-house, and built a robust framework — giving us even greater control over the reliability of our systems and the ability to quickly adapt based on whatever happens.

Ready for whatever, so you can keep browsing.
With a new self-developed tool for traffic forecasting, i.e. predicting the number of shoppers who will make purchases with Klarna during a certain time period, we’ve enabled more precise forecasting and in-depth learning. We’ll be ready for whatever gets thrown at us — which means you don’t have to waste time looking at loading screens or pull your hair over crashing apps.

An enjoyable season for all. Even our engineers.
Building products used by 150+ million consumers globally takes courage. To empower engineers who are preparing their systems for a spike in volume, we have worked hard to simplify our internal processes and remove friction. Shop with good conscience, knowing that Klarna engineers will be enjoying Black Friday as much as everyone else.

“This is an important season for everyone shopping and selling with Klarna. We’re thrilled to see our new tools in action and excited about the learnings and insights they will bring us”, says Esref Ozturk, Lead Engineer on the Continuous Readiness team.

“We want to thank Klarna engineers for their hard work in preparation for this year’s shopping frenzy. Hopefully we’ll have reason to celebrate together in January!”, highlights Tasio Mendez, Engineer on the Continuous Readiness team.




About the Continous Readiness team at Klarna
The Continuous Readiness team at Klarna was established to empower system owners to build resilient services and facilitate continuous readiness with quality, minimized effort and optimized cost in focus. Besides the engineers featured in this article, the team is led by Anu Sasidharan and Niki Horvath. Stay tuned for upcoming posts, where Anu and Niki will dive deeper into the technical aspects of peak season and flash sales management at Klarna.

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