Kafka sits at the heart of how we move data between systems at trivago. Many teams publish changes to Kafka, and downstream services consume those changes to keep user-facing features up to date—things like accommodation reviews, highlights, and other derived attributes.

About six years ago, our mobile automation setup was showing its age. It was a small, homegrown framework that had worked “well enough” for a long time, until we tried to upgrade Java and a few core dependencies. That’s when things started breaking in ways we couldn’t reasonably patch around. The framework simply wasn’t built to move forward.

Mob programming often sparks hot takes. “It’s counter‑productive.” “One person could do it faster.” “Why waste five people on one keyboard?” If that’s what it looks like in your head—one senior typing while others half‑listen—that wasn’t mob programming. Real mob programming is structured collaboration that turns a team’s combined attention into forward motion.

Modern frontend engineering is a collaborative effort of many people with different talents and expertise. Over the years, a team working together can continuously refine their ways of working, so that the different contributions fit together seamlessly and each step in the production process is in sync with the next one. Read about our team structure, our A/B test setup, and about what makes our QA team so special.

Are you passionate about AI and its potential to transform the travel industry? Then dive into our interview with Sören Weber, Senior Product Manager at trivago, as he reveals the journey from concept to reality behind trivago's innovative Smart AI Search feature. And learn how trivago's unique approach and deep integration of AI, set us apart.

As a part of the series of posts already mentioned on WARP - A Web Application Rewrite Project, we are disclosing our process of making technical decisions. We hope that you find this process helpful. Maybe you can even pull something out for your own projects.

Back in March 2022, after spending a considerable amount of effort migrating our monolithic Node.js GraphQL server from Express to Fastify, we noticed absolutely no performance improvements in production. That hit us like a bombshell, especially because Fastify performed exceptionally well in our k6 load tests in staging, where it responded to HTTP requests 107% (more than two times) faster on average than Express!

One of the many responsibilities of a Site Reliability Engineer (SRE), is to ensure uptime, availability and in some cases, consistency of the product. In this context, the product refers to the website, APIs, microservices, and servers. This responsibility of keeping the product up and running becomes particularly interesting if the product is used around the world 24 hours every day like trivago. And just like in the medical profession, someone has to be on call to react on failures and outages outside of the office hours.

From April 2020 until the end of 2021, we have put trivago’s web frontend on a new tech stack. Having moved away from a quite large PHP codebase and our home-grown JavaScript framework Melody, trivago now runs on a Next.js application, written in TypeScript.

At trivago we operate on petabytes of data. In live-traffic applications that are related to the bidding business cases we use our in-house in-memory key-value storage-service written in Java to keep data as close to calculation logic as possible.

Have you ever wondered about how to create components that not only change their appearance according to the viewport’s width but instead also transform according to their parent element’s sizing? This might be the case when you have a card component that has the classical vertical layout on mobile:

At trivago, we run webservices with complex backends in different regions around the globe 24/7. Our system is being iterated and developed on a daily basis. Naturally, mistakes will be made and something will break eventually. Engineers being on-call are the first responders to issues with negative impact on our users and the business.

trivago is the home to 500+ tech specialists from all corners of the globe – each with their own unique background and story of how they ended up here. Our trivago Tech Check-in series focuses on individual engineers' experience during their time at trivago. In this edition, you'll meet Mohammad Abed – a frontend software engineer who has been with trivago for 11 months now and is working on our Express Booking product.

While engineering, we fix bugs, create new systems, build workflows and establish processes. Our job is to change things. Changing things can involve mistakes that ultimately lead to the failure of a particular system. To learn from these failures, a retrospective is helpful to get to the root of this problem. In the tech industry, a Blameless PostMortem is the right tool for this job.