Accessibility
You do not need an audit tool to find the common problems. A keyboard and ten minutes will find most of them.
Try it with the keyboard
Tab through the page. If you cannot reach the menu, the form and the footer links, or you cannot see where you are, neither can anyone who does not use a mouse. Visible focus outlines exist for this reason and should not be switched off.
Contrast and text size
Light grey text on white looks calm in a design file and is unreadable on a phone in daylight. Body text needs real contrast against its background, and it should stay readable when the visitor zooms in.
Alt text and labels
Describe what the image conveys, and leave it empty for decoration rather than writing "image of". Every input needs a label element attached to it — placeholder text disappears as soon as someone starts typing.