Experimentation and engineering at Booking.com.
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UnlockThis blog post was written by Dennis Abrazhevich and Koen van Berge Henegouwen. The Biggest Data Migration in Europe We’ve all heard those dramatic lines in films boasting about “the largest data leak in history .” But while blockbusters exaggerate for dramatic effect, reality is often just as impressive. In this…
By optimizing our biggest Node.js service, we cut our compute costs by 38 % By optimizing our biggest Node.js service, we cut our compute costs by 38%: we ran 30% fewer pods, reduced memory usage by 20% per remaining pod, and took up to 10% off latency at p75, p99, and p99. No new hardware, and no code changes in the…
Photo by GuerrillaBuzz on Unsplash Kafka makes it easy to distribute work across consumer instances. It is much harder to prove, safely and repeatedly, how those instances behave when the distribution changes and one of them has to carry more than its usual share. For teams that run Kafka at scale, this is a…
When an urgent request for a report or dashboard arrives, often just before an executive meeting, data and engineering teams must drop planned work to respond. One request may be reasonable, but repeated interruptions come at a cost: important work, such as scaling infrastructure, improving reliability, models…
Introduction For the majority of Booking.com travelers, mobile is the primary channel for researching, planning, and booking trips. Recent data shows that over 80% of travelers rely on a mobile app during the research phase, with more than half of all bookings occurring on mobile devices. Consequently, the Android…
How a seemingly simple AWS API call can silently slow down your CI/CD pipelines Review/co researcher: Gonzalo Ulla The Mystery It started with a line in one of our team’s CI/CD logs that nobody expected: module.project.module.user buckets.module.s3 bucket.data.aws organizations organization.current: Still reading……
This post was originally published internally on May 9, 2025 and has been reworked for a public audience. Authors: Ioannis Androulidakis , Mohammed Gaafar Intro The Database Engineering team at Booking.com is constantly looking for ways to improve database reliability and support scaling our business. In 2025 we…
The necessity of imperfection: Designing for distributed ownership in Backstage Imagine an internal engineering platform — tooling that is accessed by thousands of developers every day — where every new feature, every piece of critical functionality, is designed, built and maintained by a different, autonomous team.…
Over the past 15 months I have been actively working with LLM’s in my job as a software engineer. I have had many moments where I thought singularity was here, but then almost immediately after I would see the agent fall flat on its face. I have become interested in figuring out when and why these new tools fail, in…
Unlocking the Power of Customization: How Our Enrichment System Transforms Recommendation Data Enrichments How are accurate property prices on Booking.com connected to machine learning that recommends appealing property photos? What about the number of users who have wishlisted a property? And how can developers…
