Checking PDFs
PDFs are a common accessibility gap and a frequent source of complaints. Zylyn checks them against PDF/UA-1, the accessibility standard for PDF documents.
Why this matters#
Most site audits stop at HTML. But if your contracts, forms, menus, reports, or brochures are PDFs, a screen reader user may be locked out of the most important content you publish — and document accessibility is regularly cited in legal complaints and procurement reviews.
How to check one#
Open PDF documents in the sidebar, then Add PDF. Upload a file, or paste a link: a link is downloaded and its pages counted first, so you see the price before anything is charged.
To check a document again, open its report. A document added from a link has Check again, which downloads the latest file (if it hasn't changed, nothing is checked or charged). An uploaded document has Upload a new version: the new file joins the same document's history, so the report shows what changed.
Cost: 2 credits per page. Note per page of the document, not per document — a 20-page report costs 20 credits. Check your balance before submitting a long one.
PDFs found on your sites#
You don't have to find a site's PDFs yourself. When Zylyn finds a tracked site's pages, it also notes every PDF the sitemap lists, and every scan of a page notes the PDFs that page links to, on the site's own address or a subdomain of it. Nothing is downloaded to find them. PDFs on other hosts are counted, not added: the PDFs side lists them by host under Also on other hosts, and when a host is yours (your CDN, say), Add this host lists its PDFs like the site's own, from then on too. A site can take PDFs from up to five such hosts; Stop hides the ones not yet checked again. A PDF they haven't seen (a link that doesn't end in .pdf, or a document on another host the site cares about) goes in by its link: Add a PDF link on the PDFs side puts it in the list, and its check decides whether it is a PDF; nothing is downloaded or charged until then. A Google Drive share link works too, here and in PDF documents, as long as the file is shared with anyone who has the link; the file keeps the name it has in Drive. A site keeps up to 10,000 PDFs found this way; past that a look says the sitemap lists more than a site keeps, and Add a PDF link still works for the ones that matter.
They appear on Pages, behind the Pages / PDFs switch at the top of the tab (each side shows its count): each with where it was found and whether it has been checked. Check downloads the file and counts its pages first, so you see the price before anything is charged. The report stays with the site: it opens from that list, where everyone on the team can see it, and never appears in PDF documents, which lists only what you upload or paste yourself (a file that is also on a site stays there as before). Check again downloads the latest file (unchanged, nothing is checked or charged), and a file that is already one of your checked documents is linked to that report, free. Check all PDFs takes every unchecked PDF on the site, up to 50 at a time: each is downloaded and its pages counted first, nothing kept and nothing charged, then the total shows for you to confirm; the checks then run one by one on the server, so you can leave the page, and a file that changed between the count and its check is skipped, unpaid. A PDF that can't be downloaded (a sign-in, a link that has gone) says so, and Remove takes one out of the list for good.
The four stages of a document check#
| # | Stage | What happens |
|---|---|---|
| 1 | PDF submitted | Uploaded, or downloaded from a link, one document at a time; its pages are counted and priced before anything is charged |
| 2 | Accessibility analysis | Structure, language, fonts, metadata and alternative text checked against every PDF/UA-1 requirement |
| 3 | Tag validation | Semantic tags verified for headings, lists, tables, links and form fields |
| 4 | Compliance report | Each failed requirement with where it fails and how to fix it in the source file, kept as a dated record |
What gets checked#
PDF/UA-1 conformance, which in practice means:
- Tags — whether the document has a proper structure tree (the PDF equivalent of headings and landmarks)
- Alternative text on images and figures
- Table structure — header cells properly associated with data cells
- Document language and title metadata
- Fonts — embedded, and mapped to real characters
- Links and form fields — tagged, with a description
Automated checks can't judge whether the reading order makes sense, or whether alternative text is meaningful: a person should still read each document once.
The four failures that account for most of it#
| Failure | Why it breaks | Fix |
|---|---|---|
| Untagged documents | A formatted PDF with no tag tree is unreadable in any meaningful order. The most common failure in enterprise document sets. | Re-export from source with tags enabled |
| Scanned images of text | Archived forms stored as flat images carry no text layer at all; the check reports them as untagged content | Re-issue from the source, or run text recognition (OCR) in Acrobat and tag the result |
| Fields without labels | Interactive PDFs where fields have no accessible name leave assistive technology users guessing | Add field names in the form editor |
| Tables without headers | Statement and pricing tables lose all meaning without row and column header associations | Mark header rows/columns in the tag tree |
The most common problem#
A PDF exported straight from Word, Canva, or InDesign without accessibility settings enabled is usually untagged, and an untagged PDF is close to unusable with a screen reader.
The fix is generally not in Zylyn — it's in your source document:
- Use real heading styles in the source, not manually enlarged bold text
- Add alt text to every image before exporting
- Export using "Save as PDF" with document structure or accessibility tags enabled, not "Print to PDF"
- For an existing PDF with no source file, remediation means retagging in Acrobat Pro or similar — that's specialist work, and Request remediation help is the right route
Practical advice#
Don't scan every PDF you have. Start with the ones that matter: anything a customer must read to transact with you — application forms, price lists, terms, menus, statements. A decorative brochure matters less than the form someone needs to complete to become your customer.