SEOs noticed Google began utilizing structured data markup with JSON-LD in July when it was noticed Google was displaying recipe data using JSON-LD in their search results.

Google has added support for reviews in JSON-LD since then, and it is “supported for all Knowledge Graph features, sitelink search boxes, Event Rich Snippets, and Recipe Rich Snippets.”  They also added critic review markup support in JSON-LD in August.

At SMX East last week, Gary Illyes from Google confirms that they plan to expand their support of JSON-LD across more categories.

This isn’t surprising since there are signs that Google prefers LSON-LD over other structured data formats.  In their support documents for schema, they now recommend using JSON-LD for the supported features.  “Google recommends the use of JSON-LD for those features.”

It is also possible that Google does use JSON-LD for more than the currently listed supported features, as the support documents haven’t been updated to include known supported features such as the critic review markup.  However, Google does have a structured data testing tool you can use to check whether Google is understanding JSON-LD for additional features.