What is GraphQL?

A query language for your API

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.

Ask for what you need, get exactly that

Send a GraphQL query to your API and get exactly what you need, nothing more and nothing less. GraphQL queries always return predictable results. Apps using GraphQL are fast and stable because they control the data they get, not the server.

GraphQL is a query language for your API, and a server-side runtime for executing queries using a type system you define for your data. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data.

A GraphQL service is created by defining types and fields on those types, then providing functions for each field on each type. For example, a GraphQL service that tells you who the logged in user is (me) as well as that user's name might look like this:

Along with functions for each field on each type:

After a GraphQL service is running (typically at a URL on a web service), it can receive GraphQL queries to validate and execute. The service first checks a query to ensure it only refers to the types and fields defined, and then runs the provided functions to produce a result.

For example, the query:

Could produce the following JSON result: