GraphQXL is an extension of the GraphQL language with some additional features that help creating big and scalable server-side schemas.
When following a schema-first approach, there are some challenges that are left unaddressed compared to a code-first approach.
With a code-first approach, you have all the tools the programming language you are using provides, like functions for automatically generating repetitive types, inheritance for reusing code pieces, and so on.
With a schema-first approach you need to write by hand all the repetitive entities in your schema, and if you want to split your schema across different files for a better maintainability you are bound to language-specific tools for merging them.
GraphQXL provides additional syntax to the original GraphQL language for solving this challenges and making defining server-side GraphQL schemas a nicer experience, without being bound to language-specific tools. At the end of the day, GraphQXL is just a binary executable that will compile your GraphQXL schemas into GraphQL, independently of the programming language that you are using for the backend.