A PDF that looks great on screen can be totally unusable for someone using a screen reader. No tags means no structure. No alt text means images are invisible. No language tag means everything is pronounced wrong.
Accessibility isn't binary. There's a checklist, and most PDFs fail half of it.
The four things that matter most
Tags: every paragraph, heading, table, and list needs a structural tag. Alt text: every meaningful image needs a description. Reading order: tags must be in the order a sighted reader would follow. Language: the document language must be set.
Get these four right and 80% of accessibility issues are solved.
Run an accessibility check
Open the file in Flint's editor and run the accessibility check. It flags missing tags, untagged images, missing alt text, and reading-order issues.
Fix the flagged items one at a time. Tag headings as headings (not as plain text). Add alt text to every chart, photo, and meaningful graphic. Set the document language.
Test with an actual screen reader
Tools can only catch so much. Open your PDF in VoiceOver (Mac), NVDA (Windows free), or JAWS and listen to a few pages.
You'll catch problems automated tools miss: alt text that says "image1.jpg", tables read column-first when they should be row-first, headings that don't read as headings.
Maintain accessibility through edits
Accessibility erodes when you re-export from Word or run "print to PDF". Set up your source documents with proper heading styles, image alt text, and table headers. The PDF inherits that structure.
When you merge files, check tags after merging — some merge tools strip them. Flint preserves tags through merging.
FAQ
How do I add alt text to a PDF image?
In the editor, select the image and add an Alt Text value. Keep it short — "Bar chart of revenue by quarter, 2025" is better than "image".
What's a tagged PDF?
A PDF with structural metadata — headings marked as headings, paragraphs as paragraphs, tables with row and column tags. Tags are what screen readers use to navigate.
Does my PDF need to meet WCAG?
Public-sector documents in most jurisdictions, yes. WCAG 2.1 AA is the common bar. Private documents — varies by industry and use case.
Can I add tags to a PDF that doesn't have any?
Yes, but it's manual work. Easier to re-export from a properly-styled source than to retrofit tags onto a flat PDF.
What about scanned PDFs?
Run OCR first to make the text recognisable. Then add tags. Scanned PDFs without OCR are effectively pictures — completely inaccessible.
Accessibility is a checklist, and Flint's editor walks you through it. Run the check, fix the flags, test with a screen reader.