I always say that GraphQL is best thought of as frontend code that lives on a backend server. If in your current world you have front-end code that talks to mul

I always say that GraphQL is best thought of as frontend code that lives on a backend server. If in your current world you have front-end code that talks to multiple traditional REST endpoints, the frontend is therefore responsible for managing all the relationships between the API data in order to build a coherent object graph which the UI can interpret. GraphQL turns this object graph into a first class citizen that can be consistently queried, rather than something everyone keeps having to reinvent, and moves it closer to the source of truth (the downstream services) for performance reasons (so that each network hop can be measured in single digit milliseconds rather than tens or hundreds). I've seen GraphQL schemas being implemented on the client, it's certainly doable, but the performance is terrible compared to doing it on a server close to the source of truth.