GraphQL Faker (editor for GraphQL IDL, and built-in GraphQL server to mock the future API or extend the existing API with realistic data from faker.js. No coding required, just write GraphQL IDL)
To generate documentation & test queries:
GraphiQL (in-browser tool for writing, validating, and testing GraphQL queries, can point it to a local setup or a server), has desktop app
GraphQL Playground (uses components of GraphiQL under the hood but is meant as a more powerful GraphQL IDE enabling better (local) development workflow), has desktop app
https://www.npmjs.com/package/graphql-docs (to dynamically generate a documentation explorer for GraphQL schemas, aims to provide a better overview of a schema than GraphiQL, but without querying features)