What is a schema checker?
A schema checker looks at a public HTML page and reports JSON-LD structured data found in script tags. It shows which entities parsed, which scripts are empty or invalid JSON, and the raw markup.
This checker is JSON-LD only. It does not read Microdata or RDFa.
How to check JSON-LD on a page
- Paste the page URL.
- Select Check schema.
- Review the classification: schema found, needs review, or no JSON-LD.
- Open each entity to inspect properties.
- Expand raw JSON when you need the original script.
What JSON-LD is
JSON-LD is a way to describe a page in JSON inside a script tag, usually with type="application/ld+json". Search engines already read the HTML; JSON-LD maps the page to a known type such as Product, Article, FAQPage, or LocalBusiness. That can make the page eligible for extra search details. It is not a ranking boost by itself.
JSON-LD is optional. Many useful pages have none. Missing markup is not an automatic ranking problem. Wrong or invented markup is worse than none.
What this checker reports
| Result | Meaning |
|---|---|
| Schema found | At least one JSON-LD script parsed, and entities have a usable @type. |
| Schema needs review | JSON-LD is present, but a script failed to parse or an entity is missing structure such as @type. |
| No JSON-LD found | The HTML response contained no JSON-LD scripts. |
Warnings in this version cover parse and structure only: invalid JSON, empty scripts, missing or malformed @type, and invalid roots. Schema.org property completeness is not scored here.
Common JSON-LD problems
Invalid JSON
A trailing comma, smart quotes, or a comment will make the script fail to parse. Fix the JSON first.
Empty script tags
An application/ld+json tag with no content is not structured data.
Missing @type
An object without @type cannot be classified as a Schema.org entity.
Non-HTML responses
If the URL returns a PDF, image, or other non-HTML body, this tool will not inspect it.
Schema checker FAQ
Does this checker validate every Schema.org property?
No. It checks that JSON-LD can be parsed and that entities have a usable @type. Required properties for specific types are not scored in this version.
Does it detect Microdata or RDFa?
No. This version only reads JSON-LD in HTML script tags.
When should I add JSON-LD?
Add it when the page has a clear job that matches a real type: a product, article or guide, a real FAQ, homepage or about as an organization or local business, or an event, recipe, job, or course when that is the page. Skip login, cart, filters, thank-you pages, and thin archives. Only describe what people actually see.
Is missing schema always a problem?
No. Missing JSON-LD does not mean the page will rank worse. Add it only when it matches what the page actually is. Wrong or fake markup is worse than none.
Why did a page return “This URL didn’t return an HTML page”?
The final response was not HTML (for example a PDF or JSON API). The checker only reads HTML documents.
Can I copy the raw JSON-LD?
Yes. Each detected script includes a copy control and a collapsed raw JSON view.