Free JSON-LD Validator: Check Schema Markup Online

Free tool

Runs in your browser. Nothing you enter is uploaded or stored.

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A JSON-LD validator reads structured data and tells you whether it can be parsed and whether the common properties for its type are in place. The free JSON-LD Validator accepts a JSON-LD block or the full HTML of a page, finds syntax errors with a line and column, and checks widely used schema.org types for missing required and recommended properties. It runs in your browser, so nothing you paste is uploaded or stored.

Google explains in its introduction to structured data that it uses structured data to understand a page’s content and to gather information about the web, and it recommends JSON-LD as the format.

How to use the JSON-LD Validator

Copy your JSON-LD, either the block between the script tags or the whole page source.
Paste it into the box.
Press Validate.
Read the summary: blocks read, entities found, errors and warnings.
Open each entity section to see which properties are present or missing, fix the markup and validate it again.

If you paste a full page, the tool finds every script of type application/ld+json and checks each one as its own block. That is the quickest way to audit a page that was marked up by a theme, a plugin and a developer at different times.

How to read the results

Errors and warnings mean different things, and the tool keeps them apart.

Invalid JSON: the text cannot be parsed, so nothing else can be checked. The message gives the line and column and hints at common causes such as curly quotes or a trailing comma.
@context: must point to schema.org. A missing @context is an error. The older http://schema.org form works but is noted.
Required properties: the basics a type needs to describe itself, such as headline, author and datePublished for an article. Missing ones are shown as errors.
Recommended properties: extra details that make the entity clearer, such as logo and sameAs for an organisation. Missing ones are shown as warnings.
Dates and addresses: dates should use the ISO 8601 form, and links should be full web addresses, not relative paths.

The tool checks Article types, Organization, Person, local business types, Product, FAQPage, BreadcrumbList, WebSite, WebPage, HowTo and VideoObject. Other types are read for syntax but get no property checks.

To find every structured data block on live pages, up to 20 at a time, use the structured data checker.

Common problems this finds

Curly quotes: copying markup from a document often swaps straight quotes for curly ones, which breaks the JSON.
Trailing commas: a comma after the last item in a list or object is not allowed in JSON.
A missing @context: without it the block is just data, not schema.org markup.
Relative addresses: a logo or url written as /logo.png instead of a full https address.
Dates in the wrong format: a date written as 28/10/2026 instead of 2026-10-28.
FAQ answers without text: each Question needs a name and an acceptedAnswer with text, and the same text should be visible on the page.

Worked example (illustrative)

Imagine a small business pasting the markup its theme produced for the home page. The validator reports one Organization with a name and url but no logo and no sameAs, so it shows two recommended properties as warnings. It also finds a logo written as a relative path and flags it.

The owner adds the full logo address and the links to the company’s social profiles, then validates again. The warnings clear and the summary shows no errors. Nothing on the page changed visually, but the entity is now described more completely.

This is a made-up example to show the process. Your own markup should describe what is really on your page.

Why it matters for SEO and AI search

Structured data gives search engines and AI systems an unambiguous statement of who published a page, what kind of page it is and what it contains. Broken markup is usually ignored, so one stray comma can undo the work. Checking the syntax before you publish saves a slow round of guessing later.

Complete markup also helps systems connect your pages to one clear entity, which supports the same signals that matter for traditional search. It does not guarantee a rich result or a citation.

Limits to know about

The validator checks syntax and a set of common properties. It does not follow Google’s full eligibility rules for rich results, and a page can pass here and still not qualify. For that, test the live URL with Google’s Rich Results Test.

It cannot tell whether the markup matches the visible page, which is a requirement: markup should describe content that visitors can actually see. To write new markup, use the Schema Markup Generator, and to see which structured data a live page carries, run the AI Search Readiness Checker.

Questions about the JSON-LD Validator

What is the difference between JSON and JSON-LD?

JSON-LD is JSON with a few reserved keys, such as @context and @type, that tie the data to a vocabulary like schema.org. It must be valid JSON first, which is why syntax errors stop everything else.

Where does JSON-LD go on a page?

Inside a script tag of type application/ld+json, usually in the head, though it also works in the body. Many WordPress SEO plugins add it for you.

Will passing this validator get me a rich result?

No. Rich results depend on the type of markup, Google’s current rules and the quality of the page. Passing here means the markup reads correctly and the common properties are present.

Can I paste more than one JSON-LD block?

Yes, if you paste the full HTML of a page. The tool reads each script block separately and reports on every entity it finds, including those inside an @graph.

Does the validator store what I paste?

No. It runs in your browser, so what you paste is not sent to my server. Nothing is saved for later.

If your markup is already on the site but you are not sure it is right, or you want it built properly across a larger site, my technical SEO services cover that work, and you can ask for a free audit through the contact page. You can also browse the full list of free schema markup tools.