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.

When was the last time you booked accommodation without checking its photos? Most probably never! Because having imagery information makes our decision-making process much easier and faster. However, picking up the best possible images of a hotel to show to the user is an interesting problem to solve, because it can be a naive random selection or a sophisticated machine learning model to know what the user truly wants at that moment.

When techies hear about email marketing and designing HTML emails, they typically roll their eyes and think of a very boring field of work. In this article, we hopefully can explain to you why this is wrong from our perspective. Our team built a solution that our marketers use to easily design HTML emails with predefined modules within our email marketing platform Salesforce Email Studio, which is part of the Salesforce Marketing Cloud (SFMC). This article gives you an overview of our approach as well as why and how we built such predefined modules for Email Studio on our own.

In the beginning of 2019, the trivago Magazine team decided to switch over from a JavaScript Single Page Application to Server-Side Rendering. This article describes the why, the how, and further challenges of this journey.

trivago Intelligence was born in 2013 with two main objectives: First, to provide bidding capability to the advertisers, who are listed on trivago, and second, to provide them with metrics related to their own hotels; like clicks, revenue, and bookings (typical BI data). This project faced a wave of inevitable data growth which lead to a refactoring process which produced a lot of learnings for the team. As I expect it to be useful for other teams who deal with similar challenges, this article will describe why a team started a full migration of technologies, how we did it and the result of it.

While searching for "Spa and Wellness hotels in Berlin..." I land on trivago. Surprisingly the main images of the hotels exactly reflect the spa concept that I am searching for. It helped me better compare hotels on the list for finding my ideal accommodation for my vacation!