JSON-LD Tester

Structured data and agent tools can be inspected on any website with JSON-LD Tester, a Chrome extension for technical SEOs, web developers, agencies and teams running shops and SaaS. It validates JSON-LD against the Schema.org vocabulary and detects tools sites expose to AI agents through WebMCP, an experimental Chrome API. An On-Page SEO tab covers meta tags, headings, Open Graph and Twitter data, hreflang, images with alt text, internal and external links and word count. A Headers tab shows HTTP response headers, index and follow status and a robots.txt check for Googlebot. A Tools tab links to external validators, and an inspection report can be exported as a PDF created locally. Results stay local, and the extension has no standing access to the user's pages.