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When Netflix migrated from REST to GraphQL, they faced a problem: 40+ microservices, each owning different parts of the data model. A single monolithic GraphQL gateway wouldn’t scale. Their solution? GraphQL Federation—a pattern that lets independent services contribute to a unified schema while maintaining autonomy. Let’s explore how this architecture handles billions of requests daily.

The Schema Boundary Problem

Traditional GraphQL implementations use a single schema. This works until your User service needs to extend the Movie type with watchlist data, or your Recommendations service needs to add personalized scores to existing types. Federation solves this by letting services extend types they don’t own.