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PAC vs veraPDF vs Acrobat Accessibility Checker
Short answer: PAC and veraPDF both test the PDF/UA rules that software can check; PAC is a free Windows app with a visual structure preview, veraPDF is free, open source, cross-platform and scriptable for batches. Acrobat Pro's Accessibility Checker is built into the editor and is convenient while fixing, but it is not a full PDF/UA validator. Use one of the PDF/UA validators as your final check.
Compared
| Feature | PAC | veraPDF | Acrobat Pro Accessibility Checker |
|---|---|---|---|
| Cost | Free | Free, open source | Included with Acrobat Pro |
| Platform | Windows | Windows, macOS, Linux | Windows, macOS |
| Rule set | PDF/UA (Matterhorn) plus WCAG-related checks | PDF/UA-1 machine-checkable rules (Matterhorn-based) | Adobe’s own checks |
| Batch checking | One file at a time | Folders, command line, scriptable | Action Wizard |
| Structure preview | Yes, a screen-reader-style preview | No | Tags panel |
| Output | On-screen and report | XML, HTML, text reports | On-screen panel |
When to use which
- Fixing a single file in Acrobat: use Acrobat’s checker as you go, then run PAC once at the end.
- Checking a whole website’s PDFs: veraPDF from the command line, or our free check for individual files.
- Proving work was done: keep the PAC or veraPDF report with the file, plus a note of who did a screen-reader check and when.
What none of them can tell you
All three test structure. None can tell you whether alternative text describes the image correctly, whether a heading is really a heading, or whether the reading order makes sense to a listener. The Matterhorn Protocol counts 136 failure conditions; 87 can be determined by software. Listen to the document with NVDA (free) before you sign off.
We use veraPDF for every file we fix, and every result includes a report you can keep.
Frequently asked questions
- Why do the three tools give different results?
- They implement different rule sets. PAC and veraPDF follow PDF/UA and the Matterhorn Protocol; Acrobat's checker uses Adobe's own list of checks and marks some items for manual review.
- Which one do auditors use?
- PAC is widely used for PDF/UA checks. Many organizations also record a screen-reader test, because no checker covers everything.