Free Tool
Schema Markup Validator
Paste your JSON-LD. Get a structured report on missing required fields, missing recommended fields, and the specific mistakes that weaken AEO — like string-typed authors or relative image URLs. Runs entirely in your browser.
Which Schema.org types does this check?
Article
Article schema is how blog posts and long-form content get surfaced in Google search and cited by LLMs. A complete Article entity with Person author and publisher Organization is the strongest signal.
Organization
Organization schema builds your brand entity in search engine and LLM knowledge graphs. Strong Organization markup is the foundation of AEO.
Person
Person schema builds author E-E-A-T signals — crucial for content attribution and LLM citation of individual experts.
ProfessionalService
ProfessionalService (or LocalBusiness) schema describes your business as a service provider. Essential for local search and entity disambiguation. List offerings via hasOfferCatalog, not the invalid serviceType array.
FAQPage
FAQPage is one of the highest-leverage schemas for LLM citation. LLMs aggressively retrieve FAQ-structured Q&A content when answering queries.
Product
Product schema supports rich results in Google Shopping and product comparison LLM queries.
BreadcrumbList
BreadcrumbList schema shows page hierarchy in search results and helps crawlers understand site structure.
WebApplication
WebApplication schema lets interactive tools (calculators, assessments) surface in AI answers for 'is there a tool for X' queries.
DefinedTermSet
DefinedTermSet (with DefinedTerm children) is the schema for glossaries and vocabulary pages. LLMs use it to identify authoritative definition sources.
Other types will parse but return a “not in our check library” warning. For authoritative validation of less common types, use Google's Rich Results Test.
Why schema matters for AEO
Large language models and AI search engines rely heavily on structured data to decide which pages to cite. When an LLM encounters a page with strong JSON-LD — correct @type, all required fields populated, a proper author/publisher entity graph — it has high confidence about who said what, and citation becomes much more likely.
The usual failure modes aren't syntax errors (browsers catch those). They're semantic sloppiness: a string where a Person object should be, a relative image URL that breaks when retrieved, an FAQ page with three Questions but no Answers, a Person with no sameAs links to verify their identity.
This validator runs the practical checks that actually show up in LLM citation outcomes. It doesn't try to replace the full Schema.org spec — for exhaustive validation, also run your page through Google's Rich Results Test.