WordPress accessibility checker
A WordPress accessibility checker should look at the published site, then point at the block, the Media Library, or the theme. AltGrade does that. You edit WordPress. You do not add a toolbar over it.
What the published page shows
Visitors never see the editor. They see the theme, the blocks, and the media. Set the site language in Settings, General, and keep language_attributes() on the html tag. Give every page a title. Keep a single title element. An SEO plugin that prints an empty title makes every tab useless.
Headings are the outline. Do not pick Heading 3 because you want smaller type. Change the size in the style and keep the level in order. The block editor will let you skip. The scan will flag it.
Media, forms and focus
Select the image block and fill Alternative text. Featured images take their alt from the Media Library, so fix it there if archives show the file name. Icons that mean something need a text name. Decorative icons should be hidden from assistive technology.
Form plugins must show the label and the error text. Placeholder text inside the field disappears as people type. Restore the theme skip link if a child theme removed it. Delete outline: none unless you replaced it with a visible focus style. Search the theme for positive tabindex and remove it.
How to check a WordPress site
Scan the public URL. Include the homepage, a sample post, a contact page, and any landing page built from a pile of blocks. The free scan covers up to 10 pages. Tab the header and a form. Zoom to 200 percent and confirm the call to action is still on screen.
If the site is also a shop, move to the WooCommerce page. Product loops add their own image, price and button problems on top of the theme.
What AltGrade gives you
The report names the block or the theme file in plain English. You get a score and a prioritised list. The £49 audit adds a PDF for the developer who does not have a login yet. Monitoring from £19 a month tells you when a plugin update brings a critical issue back. No tax is added.
Fix the content. Rescan the same URLs. The comparison shows what is new, what is still open, and what has gone.
A publishing checklist
Before you press Publish, check four things. The page has one h1. Images in the block have alternative text that is not the file name. Links say where they go. The form fields have visible labels.
Plugins that inject a slider, a popup or a mega menu are the usual regression. After you activate one, rescan the homepage. If a new critical issue appears, the plugin is the change. Disable it or fix its markup. Do not cover it with a toolbar.
The Media Library is the source of alt text for featured images. Edit it there, not only in one post, or the next post inherits the file name again. Retest the published URL after you update the library. Do the edit in the screen the report names, publish, and scan that URL again.
Questions
Do I need an accessibility plugin?
You need the content and the theme to be fixed. A plugin that only adds a front-end widget does not rewrite the blocks.
Where do I set the language?
Settings, General. Then confirm the theme still prints that language on the html element.
What will the checker miss?
Automated scans cannot catch every WCAG issue. Someone still needs to read the alt text and try the forms with a keyboard.