Structured Data Markup Validation and Testing Tools

Tools for testing structured data markup and rich snippet display, including microformats and marked up in microdata, RDFa, RDFa Lite and JSON-LD.

When testing vocabularies and schemas, note that error messages from validators may be related to the usage requirements of only that specific data consumer, especially validation error pertaining to required fields or required properties.

Google Structured Data Testing Tool
Google Webmaster Tools
Google's tool for validating, microformats and other structured data, and for generating previews of rich snippets in Google search results for supported types. Handles HTML marked up with microdata, RDFa and RDFa Lite.

Structured Data Testing Tool Bookmarklet
AJ Kohn
One-click access to Structured Data Testing Tool information on the page you're viewing.

Event Markup Tester
Google's tool for validating markup, with JSON-LD support.

Corporate Contacts Markup Tester
Google's tool for validating and markup, with JSON-LD support.

Yandex Structured Data Testing Tool
Yandex Webmaster
Yandex's tool for validating, microformats, JSON-LD and other structured data.

Structured Data Linter
Validation and visualization tool for microdata, JSON-LD and RDFa, along with vocabulary validation support for, FOAF, SIOC, SKOS and Dublic Core.

RDFa Play
A real-time RDFa 1.1 editor, data visualizer and debugger (beta).

Sindice Web Data Inspector
Structured data visualization and validation tool for RDF files, HTML pages embedding microformats and XHTML pages embedding RDFa (beta).

Microdata Parser
SEO Moves
HTML5 microdata parser that displays details for each microdata type.

JSON-LD Playground
A web-based JSON-LD viewer and debugger (beta).

Convert RDFa to JSON-LD [Bookmarklet]
Niklas Lindström
Extracts RDFa from the current page and displays it as JSON-LD.

Convert Microdata Examples to RDFa [Bookmarklet]
Niklas Lindström
Transforms microdata examples on the site so they display as RDFa.

Email Markup Tester
Google Developers/Google Webmaster Tools
Validator for JSON-LD and microdata, providing properties for each entity and specific error messages for invalid input.

Open Graph Debugger
Facebook Developers
Open Graph Object debugger from Facebook.