We are building a GraphQL API as an alternative to the three most common simple Wikidata Query Service (WDQS) SPARQL queries functionalities to help reduce the load off the WDQS. The documentation will be available as a special page on Wikidata using GraphiQL

Information on the prototype can be found here

The functionalities are as follows:

Labels of linked entities
Request labels of statement properties and labels of entities used as statement values within an entity

Bulk GET
Requesting data of multiple items (or any entities) at once

Inverse look up
Finding items by statement property value pairs, e.g. instance of: house cat, occupation: railway worker

Prototype ticket: https://phabricator.wikimedia.org/T399452
Investigation ticket: https://phabricator.wikimedia.org/T396983