Website Accessibility Checklist (WCAG 2.1 AA Essentials)
This website accessibility checklist covers the issues that fail WCAG most often and cause the most real problems for people using your site. Working through it won’t make you a certified auditor, but it will catch the majority of the barriers that get sites complained about, and make your site genuinely usable for more people.
It’s grouped by the four WCAG principles. For the why behind all of it, start with our guide to website accessibility and ADA compliance.
Perceivable
- Every meaningful image has descriptive alt text. Decorative images have empty alt text (alt=””) so screen readers skip them.
- Text has a contrast ratio of at least 4.5:1 against its background (3:1 for large text).
- Colour is never the only way you convey information. An error isn’t shown by red alone; it has text too.
- Videos have captions, and audio content has a transcript.
- Text can be resized to 200% without breaking the layout or cutting content off.
Operable
- Everything works with a keyboard alone: links, buttons, menus, forms, sliders. No mouse required.
- There’s a visible focus indicator so keyboard users can see where they are.
- No keyboard traps. You can Tab into and back out of every component, including pop-ups.
- A “skip to content” link lets keyboard users jump past the menu.
- Nothing flashes more than three times a second.
- Auto-moving content like carousels can be paused, and time limits can be extended.
Understandable
- The page’s language is set in the HTML (the lang attribute).
- Every form field has a visible label that’s programmatically tied to the input.
- Error messages are in text, explain what went wrong, and say how to fix it.
- Navigation is consistent from page to page.
- Link text makes sense on its own. “Download the 2026 price list,” not “click here.”
Robust
- The HTML is valid and well-structured.
- One H1 per page, and headings run in logical order without skipping levels.
- Custom widgets use correct ARIA roles and states, with no broken or redundant ARIA.
- It works with a real screen reader. Test with NVDA on Windows or VoiceOver on Mac.
How to actually test against this checklist
Use both machines and people.
Run an automated scanner first: WAVE, axe DevTools, or Lighthouse will catch mechanical issues like contrast and missing alt text in seconds. But automated tools only find a portion of WCAG problems, so treat them as a starting point, not a pass.
Then test by hand. Unplug your mouse and navigate the whole site with Tab and Enter. Turn on a screen reader and try to complete a real task, like buying something or submitting a form. Zoom the browser to 200%. The issues you hit this way are the ones automated tools miss.
Once you know what’s failing, our guide on how to make your website accessible walks through the fixes.
Frequently asked questions
What should be on a website accessibility checklist?
The essentials map to WCAG’s four principles: alt text and colour contrast (perceivable), keyboard access and focus indicators (operable), form labels and clear errors (understandable), and clean, screen-reader-friendly markup (robust). WCAG 2.1 AA has around fifty success criteria in total.
What WCAG level should my website meet?
Level AA. It’s the standard used in most legal settlements and the practical target for business websites. Level A is a minimum that leaves real gaps, and AAA is stricter than most sites can fully meet.
Can I check accessibility automatically?
Partly. Automated tools catch mechanical issues quickly, but a large share of WCAG needs manual testing with a keyboard and screen reader. Use automation to triage, then check the rest by hand.