When Google retired the original Structured Data Testing Tool, the Schema Markup Validator stepped in as the official replacement for general schema.org compliance checking. It’s maintained by the schema.org community rather than Google directly, which means it tests your markup against the full schema.org specification rather than against Google’s narrower interpretation of it. That distinction matters more than you might expect.
You can test a URL, paste in a code snippet, or upload a file. The validator runs through your markup and flags errors and warnings clearly. Errors indicate properties that are required but missing or incorrectly typed, while warnings point to recommended properties you haven’t included. I find it particularly useful for spotting type mismatches, such as using a plain string where the spec expects a URL or a number, which can cause rich results to silently fail in Google Search.
The important thing to understand is that passing this validator doesn’t guarantee your page qualifies for rich results in Google. For that you need the Google Rich Results Test. The Schema Markup Validator is broader, checking for general schema compliance across the whole vocabulary, not just the types Google supports for search features. I’d recommend running both. Use this tool first to confirm your JSON-LD is structurally correct, then use the Rich Results Test to check it meets Google’s specific eligibility requirements. Together they cover the bases that neither tool covers alone.