How to make a PDF accessible to WCAG 2.1 and PDF/UA — free and online. Test, fix structure, alt text and contrast, and pass PAC.
Maybe you've been told a PDF needs to be "accessible", or you simply want to make sure your document can be read by everyone — including people who use a screen reader. The good news: you need neither Adobe Acrobat Pro nor expensive consultants. Here is the practical guide that makes a PDF accessible to WCAG 2.1 and PDF/UA — free and right in your browser.
Accessible PDF — what does it actually mean?
An accessible PDF is a document that assistive technology (especially screen readers) can understand. The text must be real characters, not an image; headings, lists and tables must be "tagged" so they can be navigated; images must have a text description; and the document must declare its language and a title. The technical standard is called PDF/UA (ISO 14289) and is the document-specific way to meet WCAG 2.1 level AA.
Step 1: Test the document
Start with an analysis so you know what's actually missing. Upload your file to PDF.dk's WCAG tool. It reviews structure, images without alt text, missing language and title, readability (whether the text can be extracted) and colour contrast, and gives you a concrete list of problems.
Step 2: Add alternative text to images
The wizard shows each image and asks for a short description. Describe what the image conveys — not "image of…", but the real content ("Bar chart: budget split by area"). Purely decorative graphics are marked as decorative. Smart grouping means a logo that repeats on every page only has to be described once.
Step 3: Fix structure and reading order
The tool automatically builds the missing tag structure — headings, paragraphs, lists and tables — and sets the document's language and title. It also makes sure the screen reader reads the content in the correct order, which is crucial in documents with columns, boxes and headers.
Step 4: Generate and verify
Click generate and you get an accessible PDF back. The result is validated against PDF/UA before you download — and it's built to pass PAC (PDF Accessibility Checker), the free tool that is the gold standard in Denmark. Download your file and open it in PAC yourself to see the green check.
When a document is too complex
Some documents — old scans, intricate tables or files with fonts that can't be repaired — can't be fixed 100% automatically. For those, the tool offers a guaranteed-accessible version: every page gets an OCR text layer, so the file always passes PDF/UA. The text becomes OCR quality and the file a little larger, but the document becomes readable by screen readers and searchable.
The one thing no tool can fix: contrast
Colour contrast (WCAG 1.4.3) stems from the document's design — for example light-grey text on a white background — and can't be "tagged" away. The tool measures and points out the exact colour combinations that fall below 4.5:1, so you (or the designer) can fix them at the source, for example in InDesign or Word.
Best practice: fix at the source
- Use styles: Mark headings as headings in Word/InDesign — then much of the accessibility carries over on export.
- Write alt text right away: It's faster to describe an image when you insert it than to find it again later.
- Make the check routine: Run the WCAG check as a fixed step before a PDF goes online.
Ready to try? Make your PDF accessible for free now. Files are processed on EU servers in compliance with GDPR.