How to run a quick accessibility check on a PDF

Before you send a PDF to a wide audience, it helps to know whether it has the basics that screen readers and other assistive technology depend on. The PDF accessibility preflight reads a PDF in your browser and reports on a few common, easy-to-miss signals. It is a quick first pass that tells you where to look. It does not replace a full review.

What the preflight is, and what it is not

The preflight is a heuristic check: it looks for specific markers inside the file and describes what it found. It is not a PDF/UA validator, it does not certify that a document is accessible, and it is not legal advice. A report in which every line says “No issue found” does not mean the PDF is fully accessible or that it meets any law or standard. It also never changes your PDF; it only reads it.

Run the check step by step

1. Open the PDF accessibility preflight.
2. Choose a PDF with the file button, or drop it on the box. One PDF is checked at a time.
3. Press Start check. Nothing is read until you press it.
4. Read the list of results. Each one names what was checked, gives a status, says what was found, and suggests a next step.
5. To check a corrected version or a different file, press Check another PDF.

How to read the three statuses

• Issue found: the check found something that is likely to cause problems, such as a missing title or no tags at all. Start with these.
• Could not be determined: the check could not decide on its own. This happens, for example, when the PDF's structure cannot be read or there is no text to judge. A person needs to look.
• No issue found: the marker this check looks for is there. It does not prove that the thing it marks is good. A title can be set but meaningless, and alt text can exist but say nothing useful.

What each result means and how to fix it

Most fixes belong in the app that made the PDF, such as your word processor or design app. Correct the source document, export the PDF again, and run the check on the new file.

• Document title: a title has to be set in the document properties; the file name does not count. The check also looks at whether viewers are told to show that title instead of the file name. Set the title in the source app (often under File, then Properties) and export again.
• Document language: screen readers use this setting to choose a voice and pronunciation. It should be a standard code such as en or en-US. The check reads the setting only; it does not detect what language the text is actually in.
• Tags (document structure): tags tell assistive technology which text is a heading, a list, a table, or a figure. Without them, everything is read as one stream of text. Many apps have an export option such as “Create tagged PDF”; turn it on.
• Alternative text for figures: tagged figures should carry a short description. If the PDF is not tagged, its images cannot have alt text at all. The check counts missing descriptions; it does not judge whether the descriptions that exist are any good.
• Selectable text: a page without selectable text, such as a scan, gives a screen reader nothing to read. Adding a text layer with the OCR PDF tool helps with this, though it does not add tags; the guide to making a scanned PDF searchable explains the steps. Remember that OCR can make mistakes.
• Reading order: the check reports signals that the order may be a problem, such as missing tags or text stored out of visual order. It never confirms that the reading order is correct, so this always needs a person to check.

After the preflight

Fix the issues the preflight found, run it again, and then go further. For a full review, open the document in a dedicated accessibility checker, listen to it with a screen reader from start to finish, and, where you can, ask people who use assistive technology to try it. Those steps catch things no automatic check can, such as a confusing heading structure or a chart whose description leaves out the point it makes.

Limits to keep in mind

• This is a heuristic preflight, not a PDF/UA validation, accessibility certification, or legal advice.
• Some results are “Could not be determined” and need a person to look.
• Reading order is never confirmed as correct, and the quality of alt text is not judged.
• The PDF is only read. Nothing in it is changed or fixed.