The advantages are:

Combine multiple network requests into one, reduce the number of network requests between the front and back ends, and speed up the rendering of front-end pages;

Provides a very good debugging tool, GraphiQL , and can generate documents through code, saving document maintenance costs and communication costs;

It has to be said that GraphQL has many advantages as an emerging technology. Many companies are trying to use GraphQL to provide external APIs. Although this technology is not particularly mature at present, it has great potential.

https://medium.com/@mena.meseha/practice-of-graphql-in-microservice-architecture-e8f2d698f93b