The Symfony Finland site has a recent post giving an overview of GraphQL and Symfony, combing the GraphQL query language (RESTish handling) from Facebook with your application.
The origins of GraphQL stem from the needs that Facebook's mobile applications had (and continue to have). They needed a data-fetching API that was flexible enough to describe all the different kinds of data that the social network had available. [...] Back in September 2015 GraphQL was already powering Billions of API calls a day at Facebook. [...] The core idea of GraphQL is to send a simple string to the server. This string is then interpreted by the server and it sends back a JSON payload that responds to follows the structure of the query itself.
The post includes an example of what the request and response from a GraphQL query might look like for a social network's data. They also link to several PHP libraries that have come up around the functionality making it easier to integrate. There's also links to some Symfony bundles that provide functionality to make your own GraphQL servers.