Structured data is a block of code, usually JSON-LD, that tells search engines and AI systems exactly what a page is about: the business, its address, the product and its price, the article author and dates, the breadcrumb path. Google uses it to show some rich results, such as product prices and breadcrumbs, and to understand entities. Other search and AI systems read it too.
The Build tab gives you a simple form for each type. Add several, for example Organization, WebSite and BreadcrumbList, and they are combined into one @graph block that you can paste into your page or SEO plugin. Every block is checked as you build: missing required and recommended properties, dates that are not in ISO format, links that are not full URLs, prices with currency symbols, and reviews that look self-serving. The Check tab reads the JSON-LD on a live page, or code you paste, and runs the same checks, including JSON syntax errors that stop the whole block from working.
The rules follow Google Search Central’s structured data documentation, checked on 4 November 2026. Google stopped showing FAQ rich results on 7 May 2026, so FAQPage markup no longer produces a special result in Google, although it is still valid schema.org. Valid markup does not guarantee a rich result: Google decides when to show one, and markup must describe content that is actually visible on the page.