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Free PDF Accessibility Checker
Upload a PDF to check it against common accessibility requirements. Your file never leaves your browser.
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The check runs in this browser. Your file is not uploaded or stored.
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- No server calls: the PDF stays on your device.
What does a PDF accessibility checker look for?
A checker looks for the hidden structure that lets assistive technology understand a document. This quick scan tests seven useful signals:
- Tags. Headings, paragraphs, figures, lists, and tables need structural labels rather than visual formatting alone.
- Document title. A meaningful title helps people distinguish the file in a reader or browser tab.
- Language. The language setting tells a screen reader which pronunciation rules and voice to use.
- Bookmarks. Bookmarks give longer documents another predictable way to move between sections.
- Extractable text. A page made only from an image has no text for a screen reader to announce or a user to select.
- Metadata. Author, subject, and keywords make the file easier to identify and manage.
- Encryption. Some security settings can prevent assistive technology from extracting text even when the page looks normal.
No automated scan can judge whether alt text is useful, a reading order makes sense, table headers are associated correctly, or math is announced well. Use this result as a first pass, then test the document with a screen reader and a full checker such as Adobe Acrobat's accessibility check or PAC.
Tagged PDF vs. untagged PDF
An untagged PDF records where marks appear on a page. A tagged PDF adds a logical structure tree: this text is a heading, that object is a figure, and these cells form a table. Tags make navigation and reading order possible, but they still need to be correct. Read what makes a PDF accessible and then see how PDF tags work.
Why scanned and handwritten PDFs fail
A scan is usually a stack of pictures. Optical character recognition can add a text layer, but ordinary OCR often loses equation meaning, superscripts, matrices, chemical notation, and table relationships. A screen reader may receive a jumble of symbols instead of the math a sighted reader sees.
For STEM documents, the reliable fix is to reconstruct the source as real text and semantic math, then create an accessible output. Use the sample collection button below to send representative pages directly.
How to fix accessibility issues
- Start from the original Word, LaTeX, or document source when possible.
- Use real heading styles, lists, tables, and links before export.
- Add concise alt text to meaningful figures and mark decoration as artifacts.
- Set the document title and language in the source and in the PDF.
- Correct the tag tree and reading order after conversion.
- Test with a full checker and at least one screen reader.
Follow the complete step-by-step PDF accessibility guide for source documents, existing PDFs, scans, tables, and math.
Have handwritten or scanned STEM content?
Underleaf converts handwritten notes, scanned PDFs, and equations into accessible MathML, tagged PDF/UA, HTML, and clean LaTeX. Send us two or three pages for a free sample. There is no charge and no commitment.