The JSON:API module was added to Drupal 8.7 as a stable module!
See Dries’ overview of why this is an important milestone for Drupal, a look behind the scenes and a look toward the future. Read that first!
Upgrading?
As Mateu said, this is the first time a new module is added to Drupal core as “stable” (non-experimental) from day one. This was the plan since July 2018 — I’m glad we delivered on that promise.
This means users of the JSON:API 8.x-2.x contrib module currently on Drupal 8.5 or 8.6 can update to Drupal 8.7 on its release day and simply delete their current contributed module, and have no disruption in their current use of JSON:API, nor in security coverage! 1