It was a 3-round interview process.

1. HR phone interview with a recruiter.

   • The recruiter was friendly and asked general questions about my experience.
   • Questions covered booking.com's business and A/B testing.
   • I discussed my experience in more detail.

2. Technical phone interview.

   • I was given a design challenge related to improving the mobile app, which I then presented and discussed over the phone.
   • The interviewers asked about how I would test these designs and explain my decisions and why they would be impactful.

3. In-person interview.

   • This lasted about 5-6 hours and included two technical interviews.
   • One interview focused on my experience, and the other was a role-play/technical interview.
   • In the role play, I interacted with two clients who wanted to improve their business through technology. I had to identify their pain points and propose tech solutions, which led to designing an app for them.
   • Be prepared to fully defend your design decisions, ask questions, and truly understand the reasoning behind your choices (both in the role play and regarding your portfolio work).

Of the improvements you made to the mobile app, which one has the highest priority and why? How would you test its effectiveness?