Design Google Flights – Frontend System Design

We’ll walk through the frontend system design for Google Flights: a search UI that stays honest about prices that expire, dates that live in city timezones, and a result list users share, filter, and compare without a network round trip for every chip. You’ll see why the URL is the query, why a fare calendar is a cheaper index than the itinerary list, how filter chips stay local, and how Book hands off to someone else’s checkout after you revalidate a quote.

This is not a catalog search. An e-commerce filter can refetch. Flight search cannot. A full itinerary search talks to airline inventory and takes one to three seconds. Calendar prices are a separate, staler index. The number on a card is a timed quote, not a computed total. Design it like a product grid and you will refetch too often, paint the wrong day around midnight, and send people to book a fare that no longer exists.

Problem Statement

Design the frontend for a flight search product... premium content.