PDF/UA checker: how to check PDF accessibility online

What is PDF/UA?

PDF/UA (“Universal Accessibility”) is the international standard ISO 14289 for accessible PDF documents. It defines how a PDF must be built technically so that assistive technologies such as screen readers, braille displays and read-aloud tools can present its content reliably and in the correct order. In practice, PDF/UA usually means PDF/UA-1 (ISO 14289-1); PDF/UA-2 for PDF 2.0 was published in 2024.

The heart of PDF/UA is the structure tree: every meaningful piece of content is marked with a tag such as heading, paragraph, list, table, figure or link. Purely decorative elements like running headers, page numbers or rules are marked as artifacts so screen readers skip them.

What does a PDF/UA checker test?

Automated checkers verify every requirement that a machine can decide. The most important ones are:

• Tagged PDF: Is there a structure tree (StructTreeRoot) and is the document flagged as tagged (MarkInfo)?
• Document title: Is a title stored in the metadata and shown in the title bar instead of the file name (DisplayDocTitle)?
• Document language: Is a default language (/Lang) set so screen readers choose the right pronunciation?
• PDF/UA identifier: Does the XMP metadata contain the pdfuaid:part entry?
• Fonts: Are all fonts embedded and do they have a Unicode mapping (ToUnicode) so text can be read aloud, copied and searched correctly?
• Links and annotations: Is every link annotation attached to a Link tag and does it have a description?
• Tab order: Does keyboard navigation follow the document structure (/Tabs /S)?
• Figures: Do images that carry meaning have alternative text?

What automated checks cannot do

According to the Matterhorn Protocol, the PDF Association’s test catalogue for PDF/UA-1, a significant share of the requirements can only be judged by a human. Software can detect that an image has alternative text, but not whether that text describes the image meaningfully. Nor can it reliably decide whether a bold line really is a heading or whether the reading order makes sense.

Passing an automated test is therefore necessary, but not sufficient, for an accessible PDF.

How to check a PDF with EasyPDFUA

1. Open the application and select a PDF (up to 5 MB for free, up to 50 MB with Premium).
2. Check the title and document language.
3. Choose Inspect only. The document is not modified.
4. Review warnings, document properties and the structure tree in the report.

The report shows which tags exist, where title, language or Unicode mappings are missing and which links are not anchored in the structure. If problems can be fixed unambiguously, you can then create a retroactively tagged copy.

Cross-check the result: PAC and veraPDF

For a reliable statement we recommend validating every result with established tools as well:

• PAC (PDF Accessibility Checker): a free Windows application that covers the machine-checkable Matterhorn criteria and offers a screen reader preview.
• veraPDF: an open-source validator for PDF/A and PDF/UA, well suited to automated workflows.

We explain the most frequent messages from these tools in Common PAC and veraPDF errors. After that comes the manual review: reading order, heading hierarchy, alternative text and table structure.

Frequently asked questions

Is a PDF/UA check free?

Yes. With the free EasyPDFUA plan you can check PDFs up to 5 MB without entering payment details. PAC and veraPDF are also available free of charge.

Does the report certify PDF/UA conformance?

No. The report shows findings that can be detected automatically. Full PDF/UA conformance also requires a manual review of alternative text, reading order and headings, among other things.

Is my PDF changed during the check?

No. In “Inspect only” mode the document is only read. Tagging always creates a new copy; the original stays unchanged.

Which PDFs cannot be checked?

Encrypted, digitally signed or technically ambiguous PDFs may be rejected, because any change could invalidate the signature or damage the content.