GraphQL is a specifiction for a flexible and prowefull API layer created by Facebook in 2012. In recent years it has been gaining more and more popularity.
Now, its used by complanies like Airbnb, Shopify, GitHub, Audi, Coursera, Twitter and many others.
Our team is an early adoptder of GraphQL in production systems. Our experience covers complex business-domains and various system achitectures.
GraphQL could be integrated even in legacy application and it could be built on top of exsiting APIs (for example, REST).