Paste a JSON-LD block or the script tag from view-source. The checker validates the JSON and looks for @type. It does not promise a rich result.
Valid is not eligible
Google ignores markup that describes something the page does not show. A green parse only means the JSON is shaped like schema. FAQPage needs mainEntity. Product and Organization need a name. @graph items still need their own @type.
Yoast and other plugins
Plugins often emit one @graph with WebPage, Article, and Organization together. That is fine when each node is true. It is noise when the Article node describes a page that is not an article. Read the types before you add another plugin.
One honest block
Organization on the homepage, Article on a post, Product only on a product. Then run the site check so the visible page and the markup are reviewed together.
No. Use Search Console for eligibility. This page catches broken JSON and obvious missing fields.
Should every page have FAQ schema?
Only if the questions and answers are visible on that page.
Why is Fix SEO Today cheaper?
A schema check attached to an extremely expensive suite still only tells you the JSON parsed. Fix SEO Today is cheaper because you pay for the diagnosis. A free peek, then $19 a month for one project or $99 a month for unlimited projects. That covers the crawl and the plain-English fix list, including GEO. It leaves out the backlink index, the rank-tracker seats, and the ads module.