Free Structured Data Extractor (JSON-LD)

They are three syntaxes for the same schema.org vocabulary. JSON-LD is a <script> block independent of the HTML, recommended by Google; microdata (itemscope, itemprop) and RDFa (typeof, property) are written inside the tags. The tool validates JSON-LD and flags the presence of the other two.

For each rich result type (Article, Product, FAQ, Event…), Google publishes the properties without which the result is not eligible (required) and those that improve it (recommended). A missing required property is an error; a missing recommended one is a warning.

The usual causes: a comma after the last item, single quotes instead of double quotes, a comment, or unescaped HTML inside a value. The tool tells you whether a trailing comma or a comment is enough to explain the error.

No. It makes the page eligible. Google then decides based on page quality, consistency between the markup and the visible content, and its own rules (self-serving reviews, for example, are no longer displayed).

Both work. A single block with @graph lets you link entities together (WebSite → Organization → WebPage → Article) through @id, which Google and AI engines make increasingly good use of.

Article and its variants, Product and Offer, Organization, LocalBusiness and its subtypes, FAQPage, BreadcrumbList, WebSite, WebPage, Person, Event, Recipe, VideoObject, HowTo, JobPosting, Review, AggregateRating, SoftwareApplication, Service, Course, ImageObject… Other types are extracted but only checked for format.