Schema Markup Checker — Free JSON-LD Validator
Validate JSON-LD structured data markup. Paste your schema to check for errors before publishing.
Tool Interface
How does the schema checker work?
Paste either a full page of HTML or raw JSON-LD markup. If the input contains page HTML, the checker extracts every block wrapped in a JSON-LD script tag; otherwise the whole input is treated as one JSON-LD block. Each block is then validated:
- Syntax check: the block must parse as valid JSON. Blocks that fail to parse are marked as errors.
- @context check: the block should declare https://schema.org as its vocabulary.
- @type check: every entity must declare an @type, including items nested inside an @graph array.
- Duplicate @id check: entities reusing the same @id are flagged, since ids should be unique.
- Detected types: all @type values found are listed, and the parsed JSON is shown pretty-printed for review.
This checks syntax and required fields only. Google's Rich Results Test remains the authority on whether your markup is eligible for rich results in search.
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About This Tool
Validate JSON-LD Structured Data Instantly
The Schema Checker validates JSON-LD structured data for SEO. Paste either a full page of HTML or raw JSON-LD markup. If the input contains page HTML, the checker extracts every block wrapped in a JSON-LD script tag. Otherwise the whole input is treated as one JSON-LD block. Each block is then validated against the key rules search engines expect.
Checks cover JSON syntax, the schema.org @context declaration, @type on every entity including items nested inside @graph arrays, and duplicate @id detection. A Load example button shows the format instantly. The tool is free and needs no signup.
How to Use the Schema Checker
Three steps to validated schema.
- Paste your input: Drop in a full page of HTML or raw JSON-LD markup. Click Load example to see the format.
- Click Validate schema: The checker extracts every JSON-LD block and runs the validation rules.
- Read the results: Each block is marked valid or flagged with the specific problem found. Click Clear to start over.
What Gets Checked
- Syntax check: The block must parse as valid JSON. Blocks that fail to parse are marked as errors.
- Context check: The block should declare https://schema.org as its vocabulary.
- Type check: Every entity must declare an @type, including items nested inside an @graph array.
- Duplicate @id check: Entities reusing the same @id are flagged, since ids should be unique.
Key Features
- HTML or raw input: Accepts full pages or bare JSON-LD.
- Multi block extraction: Finds every JSON-LD script tag in a page.
- Four validation rules: Syntax, context, type and duplicate id checks.
- Example included: Load a sample to learn the format.
- Free and private: No signup, and nothing leaves your browser.
Frequently Asked Questions (FAQ)
Is the Schema Checker free? Yes. It is completely free with no signup.
What is JSON-LD? A format for embedding structured data in web pages using JSON, the format Google recommends for schema markup.
Can I paste a whole page? Yes. The checker extracts every JSON-LD block from the HTML automatically.
What does a duplicate @id error mean? Two entities claim the same identifier. Give each entity a unique @id.
Does it fix my schema? It identifies problems precisely so you can fix them. It does not rewrite your markup.
Is my markup sent anywhere? No. Validation runs entirely in your browser.
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