Version 1.2 of the WordPress REST API was released today. Following the last release nine months ago, version 1.2 includes a number of bug fixes, as well as other substantial improvements. The list of improvements include the addition of support for Cross-Origin Resource Sharing (CORS) OPTIONS method requests, a new filter that allows overriding full requests, better error checking and more capabilities and parameters for a number of endpoints. These improvements will be the last made to the 1.x branch of the API. A beta version for version 2.0 is expected.
The WP REST API was originally created by developer Ryan McCue to support WordPress users who "need to be able to access WordPress data in a standardised, interoperable manner." WordPress originally contained an XML-RPC API, but that was before REST and JSON took over the world, making the development of a REST API that uses JSON a more appealing option.
McCue's plugin hit the 1.0 milestone last year and has since attracted significant attention. With the goal of transforming WordPress into a full application framework that users can put to work in a variety of roles, the WP REST API plugin has been undergoing a significant rewrite and, as the version 1.2 release demonstrates, significant expansion. To date, 50 contributors have made more than 1,700 commits to the WP API on GitHub and a dedicated website has been set up containing additional information, including documentation.
Currently, the WP REST API is accessible to WordPress users as a plugin, but ultimately, the plugin's code will be made a part into the WordPress core. While a date has not yet been set for this to occur, the 2.x branch of the WP REST API plugin is expected to be merged into the WordPress core this year.