Using Accessibility Checkers

Introduction: Why use accessibility checkers (and why they aren’t perfect)

This guidance is based on WCAG 2.1 Level AA, the Web Content Accessibility Guidelines used to evaluate whether digital content is accessible to people with disabilities. Accessibility checkers are a practical first step for creating documents and course materials that work for everyone, including people who use screen readers, keyboard-only navigation, screen magnification, voice control, captions, or alternative color and contrast settings. Tools such as Microsoft Office’s built-in Accessibility Checker, Grackle for Google Docs/Slides, and Canvas Panorama can quickly identify common barriers and guide you toward fixes.
 

At their best, these checkers help ensure your content has the basic structure that assistive technologies rely on, such as:

• Real headings (so screen reader users can navigate by section)
• Proper lists and table headers (so relationships and order make sense)
• Meaningful link text
• Appropriate alternative text for images and charts
• Logical reading order (especially in slides)
• Sufficient color contrast for text and visual elements

No single checker catches everything

Automated and semi-automated checkers are helpful, but none are complete. They can help identify issues related to WCAG 2.1, but they cannot evaluate every WCAG 2.1 success criteria or replace human review. Different tools use different rulesets and have different visibility into the content, so results can vary. For example:

• Office Online vs. Desktop apps: Accessibility and other checks can differ between the desktop apps and the browser (Microsoft 365) versions, so one may flag issues the other doesn’t.  
• Grackle (Google Drive): Grackle can surface Google-specific structure issues, but it cannot apply changes. Updates must be made in the source document.  
• Panorama (Canvas): Panorama may flag accessibility issues in uploaded files or course content that are not highlighted during authoring. It may also prioritize issues differently than Office or Grackle.

Because of these differences, it is normal for two tools to report different sets of issues on the “same” document, especially if it has been converted between formats (for example, Word to Google Docs, PowerPoint to Google Slides, or either document type exported to PDF).

Use checkers as a baseline, then apply judgment

Many important accessibility decisions require human review. A checker can tell you “alt text is missing,” but it cannot always tell whether the alt text you wrote is useful. It can warn about a table, but only you can confirm whether the table is actually understandable when read linearly. Treat checkers as a baseline quality control step. They help you catch common problems efficiently, but they do not replace thoughtful design and a quick manual review.  Meeting WCAG 2.1 Level AA requires both tool-supported checking and human judgment, especially for meaning, usability, navigation, and context.

The Goal

The requirement is to meet WCAG 2.1 Level AA. The goal is not to get to zero warnings in any single accessibility checker. The goal is to ensure documents and slides are usable and understandable for all users, across devices and assistive technologies. Tools such as Microsoft Office Accessibility Checker, Grackle, and Canvas Panorama help identify likely issues and fix them earlier, but they cannot detect every WCAG requirement or confirm full compliance. Expect differences between tools and prioritize fixes that affect comprehension, navigation, and keyboard and screen reader access. For anything uncertain, review the relevant WCAG 2.1 success criteria and do a quick manual check.

Microsoft (Word + PowerPoint): Check Accessibility with Built‑in Accessibility Checker

1. Run the Accessibility Checker
   • Word / PowerPoint
     1. Open the document in Word / PowerPoint.
     2. Go to Review.
     3. Select Check Accessibility. 
     4. The Accessibility pane opens with issues and recommended fixes.
2. Fix issues
   • Most common issues the checker will find:
     • Alt text missing: Add alt text to images, charts, SmartArt/icons.
     • Headings (Word): Use built-in Heading styles (Heading 1, Heading 2…) in a logical order.
     • Links: Use descriptive link text (avoid “click here”).
     • Lists (Word / Powerpoint): Use built in list tools like for bullet points and numbered lists. Avoiding typing numbers and bullets for lists manually.
     • Tables (Word): Add header rows; keep tables simple; avoid tables for layout.
     • Color contrast: Ensure text stands out from the background.
     • Reading order (PowerPoint): Ensure content is read in the correct order by screen readers.
3. Re-check
   • Run Review → Check Accessibility again after fixes until major issues are resolved.

Google (Docs + Slides): Check Accessibility with Grackle

1. Install Grackle (one-time setup per account)
   1. Open any Google Doc.
   2. Go to Extensions → Add-ons → Get add-ons.
      • Troubleshooting: If you do not see  “Extensions”:
        • You may be editing a Word document instead of a google doc. Seeing .DOCX means you are using a Word document
        • You may be editing a PowerPoint document instead of a Google Slide.  Seeing .PPTX means you are using a PowerPoint document 
        • Convert to a Google document type by clicking File → Save As Google Docs/Slides 
   3. Search Grackle Docs/Slides.
   4. Click Install and approve permissions.
2. Run Grackle to check accessibility
   1. Open the Doc /Slide (does not work with docx or pptx files).
   2. Extensions → Grackle Docs/Slides → Launch 
      • (Missing “Extension”?  See Troubleshooting in test 1)
   3. In the Grackle panel, review the errors. 
3. Fix issues (what to correct most often)
   • Alt text missing: for images/shapes/charts
   • Headings (Docs): not used or out of order
   • Links: not descriptive
   • Lists (Docs / Slides): not formatted using built-in tools
   • Tables (Docs): missing headers / too complex
   • Reading order (Slides)
   • Color contrast problems (verify visually as well)
4. Re-check
   • Re-run scan by using the “Re-Check” button. Repeat until all issues are resolved or you have verified an item is not an issue.

Additional Resources:

• More about Grackle for Google Slides
• More about Grackle for Google Docs
• How to apply WCAG to Non-Web Information
• WCAG 2.1 Success Criteria