Before and after testing?

First, you should be aware that there is no legal definition of “ADA Compliance” for websites. While websites are required to be accessible under the ADA, there is no standard defining what that means. What you will actually be checking is compliance with the Web Content Accessibility Guidelines published by the W3C, which are commonly used in international law to define web accessibility.

All testing tools test a different subset of WCAG criteria using slightly different methods, so it’s best to use more than one tool. Meeting all tested criteria does not mean that you have a WCAG compliant site, however, as the majority of web site accessibility issues cannot be detected using automation.

I recommend using WAVE by WebAIM (https://wave.webaim.org) in the toolbar installation, *not* the web-based tool and Tenon.io. Axe by Deque is also a useful tool.