Structured Data
Paste JSON-LD to see its entities and check it: syntax, schema.org value types, and the fields Google documents for rich results (with the rule source and date).
About this tool
Paste a JSON-LD block, or the whole script tag, to list the entities in it and check the syntax, a missing @context or @type, schema.org value types such as ISO dates and URLs, and the required and recommended fields Google documents for common rich-result types.
Meeting those fields does not mean a rich result will appear. This page only checks what you paste: it does not fetch any URL or read a live page. Reading the JSON-LD, Microdata and RDFa of the page you have open is a feature of the DevKit Forge browser extension.