Use Accessibility Checkers
Keep C.A.L.M. and Use Accessibility Checkers
As part of our Choose Accessible Learning Materials (C.A.L.M.) campaign, we invite university community members to use accessibility checkers when creating, reviewing, and sharing digital content. Accessibility checkers help identify common barriers that may prevent people with disabilities from accessing information and participating fully in digital environments.
Accessibility checkers are available in many of the tools used across Virginia Tech, including Canvas, Microsoft 365, Google Workspace, and Adobe Acrobat Pro. In addition, external tools are available to check websites and PDFs. While no automated checker can identify every accessibility issue, these tools provide an efficient starting point for evaluating digital content and prioritizing remediation efforts.
Using accessibility checkers supports Virginia Tech’s commitment to digital accessibility and helps us meet university policy and the Web Content Accessibility Guidelines (WCAG). By making accessibility checking part of your regular workflow, you can improve the usability and accessibility of your content for all learners.
The Office for Civil Rights Compliance and Prevention Education (CRCPE), through ADA & Accessibility Services (ADAAS), provides guidance on digital accessibility requirements and compliance obligations. ADAAS collaborates with TLOS to support the development of accessible digital content and to provide resources, training, and outreach that advance accessibility across the university.
Why Use Accessibility Checkers?
Accessibility issues are often invisible to content creators. A document may appear fully usable to the person creating it while still containing barriers for individuals using screen readers, keyboard navigation, voice recognition software, captions, or other assistive technologies.
Accessibility checkers help identify issues such as:
Missing alternative text on images
Improper heading structure
Insufficient color contrast
Missing captions or transcripts
Reading order problems
Inaccessible tables
Missing document titles or language settings
PDF tagging issues
Website accessibility barriers
Accessibility checkers save time by helping content creators identify and prioritize issues before content is shared. While automated tools cannot replace human review, they can significantly reduce the effort required to find common accessibility barriers and provide guidance on how to fix them. Regular use of accessibility checkers promotes a proactive accessibility workflow rather than waiting until a barrier is reported by a student, employee, or community member.
Tell Me How
Accessibility checkers are most effective when they are incorporated throughout the content creation process rather than used only after a document or website is complete.
Start with the accessibility checker built into your platform.
Many tools include accessibility checkers that can identify issues as you create content:
Canvas courses → Ally
Microsoft Word, PowerPoint, and Excel → Microsoft Accessibility Checkers
Google Docs, Slides, and Sheets → Grackle
Websites → DubBot or Axe DevTools
PDFs → PREP, Adobe Acrobat Accessibility Checker, or PAC
Review issues by priority.
Review the issues identified by the accessibility checker and decide where to begin. Depending on the content and platform, begin with the approach that makes the most sense. This may mean completing quick and easy fixes first, prioritizing issues that create the greatest barriers to access, or working through issues in the order recommended by the accessibility checker. If additional support is needed, pair identified issues with the corresponding Keep C.A.L.M. Campaign or guidance within the Digital Accessibility Playbook (DAP).
Use checkers early and often.
Rather than waiting until content is complete, run accessibility checks throughout the creation process. Fixing issues while you work is typically easier than remediating an entire document later.
Remember that automation is not enough.
Accessibility checkers identify many common issues, but cannot determine whether content is understandable, meaningful, or appropriately structured. Always supplement automated checking with human review.
Re-run the checker after making changes.
After addressing identified issues, run the accessibility checker again to verify that the problems have been resolved and to identify any remaining concerns.
Show Me How
Learn About Adobe Acrobat Pro Accessibility Checker
To learn how to access, navigate, and use Adobe Acrobat Pro’s accessibility tools to evaluate and remediate PDF accessibility issues, visit TLOS Tool Finder: Adobe Acrobat Pro.
What can it identify?
Missing document tags
Reading order issues
Missing document title
Missing document language
Missing alternative text for images
Table accessibility issues
Form field accessibility issues
Color contrast and structural concerns within PDFs
Strengths
Combines accessibility testing and remediation in one application
Industry-standard tool for PDF accessibility
Provides detailed reports and manual editing capabilities
Supports advanced remediation of complex PDF documents
Includes tools for editing tags, reading order, metadata, and document properties
Limitations
Requires users to purchase an Adobe Acrobat Pro license
More advanced remediation features require training and experience
Manual remediation can be time intensive for complex documents
Some accessibility issues are easier to correct in the original source document before exporting to PDF
Tips and Best Practices
Use Adobe Acrobat Pro when PDFs require detailed manual remediation.
Begin by running the Full Accessibility Check before making changes to identify all accessibility issues.
Use the Tags panel, Reading Order tool, and Accessibility Checker together rather than relying on only one feature.
Save your work frequently and re-run the Accessibility Checker after completing remediation.
Learn About Ally
To learn how to access Ally, navigate the tool, and explore additional support resources, visit TLOS Tool Finder: Ally.
What can Ally identify?
Ally evaluates instructor-created content in Canvas, including uploaded files (PDF, Word, PowerPoint), images, and content created directly within Canvas Pages, Discussions, and the Syllabus tool. Visit Ally’s Accessibility Checklist page for more detailed information.
Strengths
Integrated into Canvas
Provides a course-wide accessibility report
Prioritizes issues by severity
Offers guidance and some automated remediation options
Generates alternative file formats for students
Limitations
Only evaluates content inside Canvas
Cannot filter or control content (e.g., unpublished or inaccessible files) contributing to the Course Accessibility Report score
Cannot determine whether alternative text is meaningful
Cannot identify every accessibility issue
Does not evaluate the quality or accuracy of captions
Does not evaluate the accessibility of external links
Tips and Best Practices
Use Ally as the primary accessibility checker for content housed within Canvas, including uploaded files and Canvas Pages.
Review the Ally Course Accessibility Report at the beginning of each semester to identify the highest-priority issues across your course.
Whenever possible, remediate original source files (Word, PowerPoint, etc.) before uploading them to Canvas rather than attempting to remediate exported PDFs.
Verify that files obtained from publishers, colleagues, or previous courses are accessible before importing them into Canvas. Visit the Digital Accessibility Playbook for guidance on reviewing and remediating files you did not author, e.g., journal articles and other PDF files, that you want to include in your Canvas course.
Re-run Ally after replacing or updating files to confirm that accessibility improvements have been recognized.
Learn About Axe DevTools
To learn how to install, navigate, and use Axe DevTools to evaluate webpages for accessibility issues, visit TLOS Tool Finder: Axe DevTools.
What can it identify?
Violations of WCAG success criteria and accessibility best practices including:
Color contrast failures
Missing form labels or control names
ARIA errors
Missing landmarks and page structure issues
Keyboard accessibility concerns
Invalid HTML and accessibility attributes
Interactive element accessibility issues
Images and other non-text content that don’t have alternative text but are not marked as decorative
Instances where the appearance of elements doesn’t match how they are defined programmatically
When the page language is missing or improperly specified
Table data markup issues
<video> elements that are missing captions
Missing page or frame titles
Strengths
Free browser extension
Evaluates webpages directly within the browser
Lets you put the page in a particular state before testing
Highlights issues on the page
Provides detailed explanations and remediation guidance
Maps issues directly to applicable WCAG success criteria
Excellent for evaluating individual webpages during development
Provides useful context by letting you see where in the code the violation occurs
Limitations
Evaluates one webpage at a time
Requires some familiarity with webpage structure
Cannot determine whether content is understandable or meaningful
Does not replace manual keyboard or screen reader testing
Tips and Best Practices
Use Axe DevTools while developing or editing webpages to identify issues before publishing.
Re-run scans after making accessibility changes to verify that issues have been resolved.
Combine Axe DevTools with keyboard-only navigation and screen reader testing for a more complete accessibility review.
Read the detailed guidance provided (why the issue matters and how to fix the problem) when violations are found.
Evaluate all page templates and unique page types, not just the homepage as well as components that are used repeatedly throughout the site.
Learn About DubBot
To learn how to access, navigate, and use DubBot to evaluate the accessibility and quality of website content, visit TLOS Tool Finder: DubBot.
What can it identify?
Accessibility issues and best practices across webpages based on WCAG
Broken links and redirects
Spelling errors
University style
PDF accessibility
Basic Search Engine Optimization (SEO)
Strengths
Scans entire websites as well as individual pages
Provides detailed reports and dashboards
Identifies both accessibility and website quality issues
Helps prioritize issues based on severity
Supports ongoing monitoring of websites
Limitations
Primarily relies on automated testing
Cannot determine whether alternative text or content is meaningful
Cannot evaluate the overall usability or clarity of content
May identify false positives that require manual review
Does not replace manual accessibility testing with assistive technologies
Tips and Best Practices
Use DubBot to scan entire websites or sections of a website rather than individual webpages.
Prioritize issues identified on frequently visited webpages before addressing lower-traffic content.
Review broken links, spelling, and PDF reports in addition to accessibility findings.
Check regularly to identify newly introduced accessibility issues.
Supplement automated scans with manual testing using keyboard navigation and assistive technologies.
Learn About Grackle
To learn how to access, navigate, and use Grackle to evaluate content in Google Docs, Google Slides, and Google Sheets, visit TLOS Tool Finder: Grackle.
What can it identify?
Missing headings
Missing alternative text
Table accessibility issues
Reading order concerns
Missing document language settings
Structural accessibility issues
Strengths
Designed specifically for Google Workspace
Provides accessibility reports and remediation guidance
Supports exporting more accessible PDFs
Helps identify issues before content is shared
Limitations
Requires the Grackle add-on
Cannot identify every accessibility issue
Some issues require manual review and testing
Tips and Best Practices
Run Grackle before sharing Google documents or exporting them to PDF.
Use built-in headings, lists, tables, and slide layouts to improve accessibility and reduce remediation later.
Export PDFs using Grackle’s Export to PDF feature whenever possible instead of Google’s standard PDF download to preserve accessibility information.
Review documents manually after Grackle completes its scan, as automated tools cannot identify every accessibility issue.
Learn About Microsoft Accessibility Checker
To learn how to access, navigate, and use the Microsoft Accessibility Checker to evaluate Word documents, PowerPoint presentations, and Excel spreadsheets, visit TLOS Tool Finder: Microsoft Accessibility Checker.
What can it identify?
Missing alternative text
Improper heading structures
Reading order concerns
Table accessibility issues
Missing slide titles
Missing document properties
Some color contrast concerns
Strengths
Built directly into Microsoft Office
Provides real-time accessibility guidance
Identifies issues while content is being created
Provides instructions for fixing identified issues
Limitations
Does not identify every accessibility issue
Limited evaluation of color contrast
Cannot determine whether alternative text is meaningful
Does not fully validate exported PDFs
Tips and Best Practices
Set the accessibility checker to run automatically in the background while you compose content by selecting the “Keep accessibility checker running while I work” checkbox within the Check Accessibility Tab > Options: Accessibility.
Apply built-in headings, lists, tables, and slide layouts instead of manually formatting content.
Share the original Office file whenever appropriate, as native Office documents often provide a better accessibility experience than PDFs.
If exporting a file to PDF, ensure you are exporting the document properly to retain accessibility.
On a Windows device, select File → Export → Create PDF/XPS.
On a Mac device, select Save As → export as PDF → ensure the “Best for electronic distribution and accessibility” button is selected, rather than “Best for printing.”
Review the file using PREP, Adobe Acrobat Pro, or PAC to verify that accessibility features were retained.
Learn About PAC
To learn how to access, install, and use PAC to evaluate PDF accessibility and PDF/UA compliance, visit TLOS Tool Finder: PAC.
What can it identify?
PDF/UA compliance issues
Missing or incorrect document tags
Reading order problems
Missing document metadata
Logical structure issues
Accessibility errors that may impact screen reader users
Overall PDF accessibility compliance
Strengths
Free PDF accessibility validation tool
Excellent for verifying PDF/UA compliance
Includes a Screen Reader Preview to simulate the reading experience
Provides detailed reports for accessibility testing
Ideal for final accessibility verification after remediation
Limitations
Available only for use on Windows devices
Validation tool only; it cannot remediate accessibility issues
Requires another tool, such as PREP or Adobe Acrobat Pro, to correct identified issues
Tips and Best Practices
Review both the accessibility report and the Screen Reader Preview to better understand how assistive technologies interpret the document.
Use PAC to verify that tagged PDFs exported from Word, PowerPoint, Google Docs, Canva, or InDesign retained their accessibility features.
Address issues identified by PAC using PREP or Adobe Acrobat Pro before distributing the document.
Remember that PAC evaluates accessibility but does not remediate accessibility issues.
Learn About PREP
To learn how to access, navigate, and use PREP to evaluate and remediate PDF accessibility issues, visit TLOS Tool Finder: PREP. The Tool Finder includes instructions for requesting access, using the self-service platform, and selecting the most appropriate remediation pathway for your documents.
What can it identify?
PREP includes a built-in accessibility checker that evaluates PDF documents for common accessibility issues, including:
Missing or incorrect document tags
Reading order issues
Heading structure
Missing document title and language settings
Missing alternative text
Table accessibility concerns
Form accessibility issues
General PDF accessibility and PDF/UA compliance issues
In addition to identifying issues, PREP can automatically remediate many common accessibility barriers using artificial intelligence.
Strengths
Designed specifically for PDF accessibility remediation
Uses AI to automate much of the remediation process, including tagging headings, lists, and tables
Includes a built-in accessibility checker to review documents before and after remediation
Offers multiple service options, including self-service, AI-powered remediation, TLOS-funded vendor remediation, and fee-based remediation
Browser-based platform that can be accessed through Virginia Tech Single Sign-on
Significantly reduces the amount of manual PDF remediation required for many documents
Limitations
Self-service access requires a PREP license issued by TLOS.
AI remediation is most effective for text-based PDFs and may not accurately remediate complex tables, charts, handwritten content, mathematical notation, or intricate page layouts.
Automated remediation should always be reviewed for accuracy before distributing documents.
Tips and Best Practices
Whenever possible, create accessible documents in the original authoring application (Word, PowerPoint, Google Docs, etc.) before exporting to PDF. PREP works best as a remediation tool rather than a replacement for accessible document creation.
Use PREP’s AI-Powered Remediation service for straightforward text-based PDFs that require quick remediation.
For highly complex PDFs containing mathematical notation, handwritten content, complex charts, or extensive tables, request Assigned PDF Remediation through TLOS or consider manual remediation in Adobe Acrobat Pro.
Always review PREP’s remediated output before distributing documents. AI-generated tags, reading order, and image descriptions should be verified for accuracy.
If a self-remediation license is not available, explore the additional remediation services offered through PREP, including TLOS-funded remediation (when approved) and fee-based vendor remediation options.
Join the Campaign
Our goal is to increase the use of accessibility checkers throughout the university’s digital ecosystem. You can help us get there by sharing examples of how accessibility checkers improved your documents, websites, presentations, PDFs, or Canvas courses using @VT_TLOS #CALMAccessibilityCheckers or by emailing examples to assist@vt.edu. Every entry is eligible for some of our Keep C.A.L.M. swag.