Booking.com runs over 1,000 A/B tests simultaneously

Booking.com runs well over a thousand simultaneous A/B tests from its Amsterdam headquarters on an experimentation platform built in the mid-2000s and patched continuously without ever being fully rewritten. A single button colour test reportedly earned more than the company's first three years of trading combined. Booking Holdings processed $165.6 billion in gross travel bookings in 2024.