JSON:API is a core module that exposes Drupal content as a standards compliant JSON:API. It follows the specification at jsonapi.org, which defines how resources, relationships, and errors should be structured.
Once enabled, JSON:API automatically exposes all content entities without any configuration. You can read and write nodes, users, taxonomy terms, and custom entities through predictable URLs like /jsonapi/node/article.
The module handles filtering, sorting, pagination, sparse fieldsets, and including related resources. This makes it ideal for headless Drupal setups where a front end framework consumes content through an API. JSON:API is the recommended approach for exposing Drupal content to external applications because it is in core, follows a widely adopted standard, and requires almost no configuration. It is a huge improvement over the older custom REST endpoints.