PDF Accessibility Checker (PAC) for Windows Computers
PAC is a globally used, free PDF accessibility checking tool that can be used on Windows computers. PAC can check many PDF/UA and WCAG requirements at the touch of a button. In addition to this, PAC also provides guidance on how to perform manual checks. PAC is considered more reliable from a data quality standpoint than Adobe Accessibility Checker, but if you are on a Mac computer, you will need to use the Adobe Accessibility Checker.
Adobe Accessibility Checker for Mac Computers
Anyone using a Mac that needs to check the accessibility of a PDF can use the Adobe Accessibility Checker. Note that this checker can produce false positive and negatives so manual testing with assistive technology is also an essential step with this checker.