Allegro is a leading Central European e-commerce platform, offering a vast diversity of new and pre-owned products. Search engine is the main entry point to allegro.pl product stock. Designing a bunch of UX metrics for a SaaS solution or a social networking site is a must. Typically no one would dare discuss whether it is worth our time to measure the effect of changes through an A/B test or a focus group and monitor the impact on metrics. When it came to search engine — a back office product with almost no interface — we had our doubts. We are the search team behind the Allegro search engine. This is the complete interface of our product: