Google Search as of last week now supports syntax graph merge. This allows you to use two different forms of structured data, such as JSON-LD and Microdata, on the same page, and Google will support both.
This was announced yesterday at the Google Search Central Live event in Zurich. Ryan Levering, a Software Engineer at Google who works a lot of structured data, presented this news.
He said that syntax graph merge support "allows one to take advantage of the benefits of multiple syntaxes." He said Google has updated validator.schema.org, the Google rich result test and "all Google ingestion."
Ryan explained this to be a "somewhat advanced feature, adding that this "launched last week."
Here is a photo Aleyda Solis took of the slide where he announced this, she posted this on X, "Launched last week: syntax graph merge json-ld and microdata. Use it carefully tho! It should allow you to take advantage of the multiple syntaxes."
Note, Google Search did support understanding multiple structured data types on the same page already but now I guess it is more supported with this new syntax graph merge. Ryan explained, "the change is that the different syntaxes can now connect together. So you could implement the Breadcrumb markup in JSON-LD but reference a WebPage node that's in Microdata. It was motivated by some platforms that needed to connect markup together that are generated by different libraries/plugins."
Ryan posted again on Mastodon, "As I said in several forums, please use carefully only when necessary."
Update: Jarno van Driel pinged me that he has more technical details on LinkedIn.
Forum discussion at X.
