A11yPDF: Bridging the Gap to Inclusive PDFs
Wajdi Aljedaani, Sandeep Kumar Rudhravaram, Akhila Chintham, Abdulrahman Habib, Marcelo M. Eler · 2024 · Proceedings of the 21st International Web for All Conference (W4A) · doi:10.1145/3677846.3677859
Summary
This technical note introduces A11yPDF, a free web-based tool for evaluating the accessibility of PDF documents against WCAG 2.2 guidelines. The tool addresses key limitations of existing PDF accessibility checkers such as PDFA Inspector, PAVE, ABBYY FineReader, Common Look, and Adobe Acrobat Pro Accessibility Checker — namely their cost-prohibitive licenses, incomplete evaluation coverage, and complex usage and reporting. A11yPDF assesses ten key features of PDF documents: page header, page footer, page number, links and hyperlinks, page contrast, image description (caption), table description (caption), dyslexia friendliness, font size, and color blindness adaptations. The tool works by receiving a PDF file, extracting images from each page, and computing accessibility ratings for each feature. These individual ratings are then aggregated into a single overall accessibility score. The contrast evaluation extracts RGB values from corner pixels of each image and calculates luminance-based contrast ratios. The paper positions A11yPDF as a user-centered accessibility analyzer designed to empower even novice users to identify and address accessibility barriers in their PDF documents, lowering the technical barrier to creating accessible content.
Key findings
A11yPDF provides comprehensive coverage of PDF accessibility elements identified as important in the literature, whereas existing tools often evaluate only a subset of these elements. The tool is entirely free, removing the financial barrier that prevents many content creators from checking their documents — tools like Common Look and Adobe Acrobat Pro require paid licenses that can be prohibitive for individuals, small organizations, and educational institutions. The tool generates easy-to-read reports with actionable guidance, in contrast to existing tools whose reports can be difficult for non-experts to interpret. By evaluating elements like dyslexia friendliness and color blindness adaptations alongside more traditional checks like alt text and document structure, A11yPDF takes a broader view of PDF accessibility than many competitors. The tool is web-based, requiring no software installation, which further reduces adoption barriers. Despite established guidelines like PDF/UA-1 and the Matterhorn Protocol, numerous studies have shown low compliance rates for PDF accessibility standards, indicating a clear need for more accessible evaluation tools.
Relevance
PDF accessibility remains one of the most persistent challenges in digital accessibility. Documents shared across education, government, and business are overwhelmingly in PDF format, yet most lack basic accessibility features like tagged structure, alt text for images, and proper reading order. For accessibility practitioners, A11yPDF offers a free alternative to expensive commercial tools, making it particularly valuable for organizations with limited budgets or for individual content creators who want to check their work. The tool's focus on plain-language reporting addresses a real gap — many existing checkers produce technical output that only accessibility specialists can interpret. However, as a two-page technical note, the paper provides limited detail on validation methodology or accuracy benchmarks compared to established tools, which practitioners should consider when incorporating it into their testing workflows. A11yPDF is best positioned as a complementary first-pass tool alongside more comprehensive manual review.
Tags: PDF accessibility · automated testing · accessibility evaluation · document accessibility · WCAG · tools
Standards referenced: WCAG 2.2 · PDF/UA-1 · Matterhorn Protocol