Dual Lab Launches Quarterly Reports on PDF Accessibility Trends based on Common Crawl data

[Julia Katash]

Dual Lab announces the upcoming publication of a new analytical report on PDF Accessibility Trends from  the Common Crawl dataset.  Such deep analytical reports will be released quarterly and will provide data-driven insights into global PDF trends. The first report  analyzes 15 million PDF documents from the CC-MAIN-2026-04 Common Crawl archive.

Mild growth of Tagged PDFs share

As a preview we present a sample report showing the share of Tagged PDFs among all PDFs in the Common Crawl dataset, grouped by the document creation month.

Our analysis shows a mild increase in the proportion of tagged PDFs over the past three years. The share has been growing by approximately 1.5 percentage points per year, surpassing the significant milestone of 50% in mid-2025.

This means that today, more than half of newly created PDF documents appearing in the Common Crawl archives include structure tree with semantic information.

Why Tagged PDFs Matter

Tagged PDFs contain a structure tree that defines headings, paragraphs, tables, figures, and other semantic elements. This structure is essential for:

• The ability of Screen readers to understand the document

• Logical reading order

• Compliance with accessibility standards such as PDF/UA

• Alignment with WCAG requirements

The growth in tagged documents indicates a positive global shift toward better structured and potentially more accessible PDF publishing.

Trend in the Share of Tagged PDFs Among All PDFs

Dual Lab analyzed 15 millions of PDF documents from the Common Crawl dataset CC-MAIN-2026-04 to examine how the share of tagged PDFs has changed over time.

The results show a clear rising trend over the past three years. The proportion of tagged PDFs documents containing a structural tag tree has increased steadily by approximately 1.5 percentage points per year.

A key milestone was reached in mid-2025 (July), when the share exceeded 50% for the first time. This indicates that more than half of newly created PDF documents indexed in Common Crawl now include structural tagging.

The growth reflects broader adoption of structured document generation tools and increasing awareness of accessibility and machine-readability requirements. While the trend is positive, continued monitoring is essential to evaluate not only the presence of tags but also their structural quality.

Reports by Dual Lab

Dual Lab aims to provide objective data that supports users, accessibility experts, and organizations working toward more inclusive digital content.

The first full report will be published soon.