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Plaintools

Schema checker

A schema validator tests whether your structured data follows Schema.org specifications and includes the properties search engines need to understand your page. Paste raw JSON-LD markup or an HTML script tag snippet to run an instant schema check on syntax, context, type declarations, and required fields across common entities like Article, Product, FAQPage, and BreadcrumbList. You immediately see structural errors, missing recommended properties, and rich snippet warnings with exact path locations. Everything runs locally in your browser without calling third-party APIs, so your schema markup, draft copy, and private URLs are never sent to a server.

Local Checks OnlyRuns 100% in your browser · No network calls to Google · Nothing uploaded
Presets:

Paste raw JSON-LD or a <script type='application/ld+json'> snippet.

Schema Syntax & Shape Valid

Found 1 schema node across 1 script block.

0 issues
Article(How to Build Fast Web Applications)
Basic Shape Valid
No structural issues found for this schema type. Required properties and @context declaration are present.

About Plaintools Schema Checker:

This tool performs strict local syntax and structural verification against Schema.org specifications for common rich snippet types (FAQPage, HowTo, Article, Product, LocalBusiness, BreadcrumbList, Organization, Person). It checks required and recommended fields, @context declarations, and sub-object schemas. It is entirely client-side and does not submit URLs or content to Google, Bing, or third-party validation servers.

Schema checker example

Article with author and datePublished

An Article schema with headline 'Optimizing Web Performance', datePublished '2026-03-15', and an author Person object validates with 0 errors and generates rich snippet guidance.

Schema checker how-to

  1. Extract JSON-LD blocks from <script type="application/ld+json"> tags, or use raw input directly.
  2. Parse JSON. If syntax error occurs, return parse error with line context.
  3. Traverse top-level object, array of objects, or @graph array nodes.
  4. Verify presence of '@context' (must reference schema.org) and '@type'.
  5. Check type-specific required/recommended fields: FAQPage (mainEntity array with Question name and acceptedAnswer text), HowTo (name, step list with text/name), Article (headline, author, datePublished), Product (name, offers with price/currency), LocalBusiness (name, address), BreadcrumbList (itemListElement with position and name/item).
  6. Aggregate errors, warnings, and suggestions. Output structured validation report.

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Schema validator & schema check FAQ

What is a schema validator and what does a schema check do?
A schema validator checks structured data (such as JSON-LD) against Schema.org vocabulary specifications to ensure search engines can parse your content. A schema check inspects syntax, confirms '@context' and '@type' declarations, and verifies required entity properties like author on an Article or acceptedAnswer on an FAQPage. Running a local schema check before publishing catches missing fields that prevent rich results in search engines.
How do I validate JSON-LD structured data with this schema checker?
Paste your raw JSON-LD code or an entire HTML <script type="application/ld+json"> snippet into the input box. The validator automatically parses the code, identifies each schema node or @graph array element, and checks required and recommended fields for each detected type. Any syntax mistakes, missing context declarations, or absent properties appear instantly with clear severity tags and field paths.
What is the difference between a schema validator and Google's Rich Results Test?
A schema validator evaluates whether your markup follows valid Schema.org vocabulary rules, whereas Google's Rich Results Test evaluates whether that markup qualifies for specific Google search feature badges. This checker runs 100% locally in your browser for rapid testing without network requests, while Google's tool fetches live URLs and applies Google-specific feature eligibility guidelines.
What schema types and entities does this validator check?
It performs dedicated structural and property checks for FAQPage, HowTo, Article (including BlogPosting and NewsArticle), Product, LocalBusiness, BreadcrumbList, Organization, and Person. It also validates JSON-LD syntax, @context references, and @type definitions for any Schema.org type, including complex @graph arrays.
Can I paste HTML containing <script type="application/ld+json"> tags?
Yes. The validator extracts all <script type="application/ld+json"> blocks from HTML source code automatically and checks each schema block independently. You can paste a full web page header or template snippet directly without manually stripping the surrounding HTML tags.
What is the difference between schema errors and warnings in this checker?
Errors indicate fatal issues that prevent search crawlers from reading your structured data, such as invalid JSON syntax, missing '@context', missing '@type', or absent mandatory properties. Warnings indicate missing optional fields (like publication dates, image URLs, or brand names) that do not break the schema but help search engines display richer search snippets.
What are the most common Schema.org validation errors?
The most frequent Schema.org errors are trailing commas before closing braces, missing '@context': 'https://schema.org', omitting '@type', and forgetting required child objects like missing 'acceptedAnswer' within FAQPage questions or omitting 'author' on Articles.
Is my structured data or website content uploaded?
No. All JSON parsing and schema validation run entirely client-side in your browser memory. No text, schema markup, or URLs are ever transmitted across the network or stored on any server.