WAVE Accessibility Checker
WAVE® is a suite of evaluation tools that helps authors make their web content more accessible to individuals with disabilities. WAVE can identify many accessibility and Web Content Accessibility Guideline (WCAG) errors, but also facilitates human evaluation of web content. WAVE is accessible through a browser extension, as well as through the WAVE website. It's provided by the WebAIM project at the University of Utah. It is the most commonly used web accessibility checker, and the tool of choice for many regulators and others wishing to check the accessibility of websites.
Using WAVE
When you click on the WAVE extension in a browser, or enter the webpage URL in the WAVE website, it creates an overlay on the page, showing you where potential accessibility errors may be.
The Summary, on the left side, provides a good overview of where issues may be found. This is a good report, with no errors and no contrast errors, just some alerts. Alerts need to be checked individually, but may or may not be an actual issue. There are also tags throughout the page, highlighting important elements in the code.
In the Summary is a Details tab, which outlines specifically which errors have been identified. If at all possible, it's best to not skip heading levels, as noted in the report. Possible headings are usually flagged for text that is in paragraph-bold, prompting the review of whether it should be a paragraph or a heading.
Other key tabs include tab order for someone using keyboard controls and contrast. The contrast tab will show where there are contrast errors and how to fix them.