Accessibility Helper adds three specific improvements to your pages: a skip-to-content link, a visible focus ring for keyboard users, and a text-size control each visitor can set and keep.
It does not make your site compliant with WCAG, the ADA or the European Accessibility Act, and it is not a substitute for an accessibility audit. The settings panel says so too, above every control, in all twelve languages.
What it deliberately does not contain: no screen-reader mode, no dyslexia font, no "epilepsy-safe" mode, no automatic ARIA repair, no compliance badge. Those are the standard contents of an accessibility overlay. A blind visitor already has a screen reader tuned to their own voice and rate; a widget announcing the page over it is a second system fighting the one they chose, and it makes the site worse for exactly the people it names.
For any owner who wants the basics done properly: a keyboard user can reach the content, see where they are, and make the text bigger. And pointedly, for the owner taking an overlay off and wanting something real instead.
It loads nothing from anyone: no font, no script, no analytics, no call home. Free, no account, nothing held back.