GraphQLConf 2025

HotelPage Service (HPS) is one of the busiest, most business-critical systems at Booking.com — originally built as a REST API with Protobufs for speed and structure. It was fast but rigid. As product demands grew and clients needed more flexibility, cracks began to show: over-fetching, unclear ownership, and slow iteration cycles.

This talk shares our real-world journey of modernizing that stack with GraphQL — not just adopting it as a new interface, but transforming how teams design schemas, collaborate across domains, and scale under load. We’ll walk through how we evolved from a proto-backed monolith to a federated GraphQL architecture — improving performance, enabling resolver ownership, and making the schema reflect real product needs.

Whether you're planning a GraphQL migration or scaling one across teams, this talk delivers actionable insights and hard-won lessons from operating at billions of requests per day.

Attendees will gain:
- Align schema design with client and product needs
- Handle organisational complexity in federation
- Avoid pitfalls like over-fetching and the N+1 trap
- Drive resolver ownership and collaboration
- Optimise execution paths under high traffic