Why Acrobat and CommonLook Produce Different PDF Accessibility Results
Question details
Users notice discrepancies in accessibility reports where Acrobat Pro passes a PDF, but CommonLook flags WCAG or PDF/UA compliance issues.
- Product
- PDF Validation Tools
- Device & OS
- not provided
- Scenario
- Validating PDF accessibility for strict WCAG or PDF/UA standard compliance.
- Observed behavior
- Acrobat's built-in accessibility checker reports the PDF as accessible, while CommonLook identifies remaining structural, tagging, or nesting issues.
Ensure you clearly understand the specific accessibility standards your organization requires (such as WCAG 2.1 AA or PDF/UA) before evaluating the validation results.
Use Dedicated Validators for Complete Compliance
Rely on Acrobat for initial checks, but use dedicated validation tools like CommonLook or PAC for full PDF/UA compliance.
Acrobat's built-in accessibility checker is an excellent tool for an initial review, but it only evaluates a subset of WCAG requirements and is not a complete PDF/UA validation tool.
Additionally, editing or saving documents in Acrobat can sometimes alter PDF tags, nesting, and structure, leading to discrepancies when the same file is checked in more stringent tools like CommonLook.
Use the Accessibility Checker in Adobe Acrobat Pro to catch basic errors like missing alternative text, missing document language, or title issues.
Export the PDF and open it in a specialized validation tool such as CommonLook PDF Validator or the free PAC (PDF Accessibility Checker) to evaluate strict PDF/UA compliance.
Navigate the document manually using a screen reader (such as NVDA or JAWS) to verify reading order, logical structure, and contextual accuracy of alt text.
Create Source Documents Seamlessly with WPS Office
While specialized tools handle deep accessibility validation, WPS Office provides a lightweight, free, and highly compatible suite for creating and formatting your source documents before converting them to PDF.
- 1. Draft your content: Open WPS Writer, Spreadsheet, or Presentation to easily draft and structure your source content.
- 2. Export to PDF: Navigate to the Menu and click 'Export to PDF' to generate a standard PDF file.
- 3. Proceed to validation: Take the exported PDF to your preferred accessibility validation tool for final WCAG or PDF/UA checks.
Frequently Asked Questions
Why does Acrobat change PDF tags when saving?
When Acrobat processes a document during saving or editing, it may attempt to optimize or restructure the file. This background process can inadvertently alter manual tagging or nesting created by other specialized accessibility tools.
What is the PAC tool?
PAC (PDF Accessibility Checker) is a free, dedicated validation tool designed specifically to check PDFs against the strict PDF/UA (Universal Accessibility) standard, offering deeper structural insights than standard checkers.
Can automated tools fully guarantee WCAG compliance?
No. Automated tools can only check a subset of WCAG requirements. Structural logic, reading order, color contrast context, and the accuracy of alternative text always require manual verification by a human tester.
Which tool should I use first for PDF accessibility?
It is generally recommended to use your source authoring tool's built-in checker or Acrobat's accessibility checker for an initial pass to fix surface-level issues, followed by dedicated tools like CommonLook or PAC for strict compliance validation.
