Automating PDF Accessibility at Scale

PDF accessibility is no longer optional. Regulations and standards such as PDF/UA and WCAG are rapidly becoming mandatory across industries. For organizations producing large volumes of documents, accessibility is not just a technical requirement — it is an operational challenge.

PDFix set out to solve exactly that challenge: how to make accessibility remediation scalable, reliable, and efficient. But achieving that goal is far from straightforward.

Accessible PDFs must meet a wide range of technical requirements. Documents need correct structure and tagging, images require alternate descriptions, and metadata must be properly defined. Among all these requirements, one area consistently stands out as particularly difficult: font handling.

For assistive technologies to interpret text correctly, fonts must not only be embedded but must also include an accurate mapping between visual characters and Unicode values. Without this mapping, screen readers cannot interpret text correctly. In practice, font-related issues are one of the main reasons documents fail accessibility validation.

And validation is what matters. For most organizations, accessibility is measured in a simple way: does the document pass validation, yes or no? Do we get the green checkmark? When thousands – or even hundreds of thousands – of documents are involved, manual correction is simply not an option. Automation becomes essential.

Building for Scale

PDFix has developed a platform designed specifically to address accessibility at scale. Their technology is available in multiple forms:

• PDFix SDK for integration into automated workflows
• PDFix Desktop for interactive remediation
• Automated workflows combining multiple processing steps

Many PDFix customers operate in high-volume environments such as transactional printing, enterprise reporting, or large document archives. These environments typically generate documents from templates, meaning that the same issues occur repeatedly.

This repetition is exactly what makes automation powerful: once a workflow is defined, it can be applied consistently across large document sets. However, while many accessibility issues can be addressed systematically, some problems require deep PDF expertise – especially when it comes to fonts.

The Turning Point: Solving Complex Font Issues

During the development of their platform, PDFix encountered a critical challenge. “Accessibility remediation requires extremely precise handling of fonts and text semantics. Implementing that level of PDF processing ourselves would have required years of development,” says Jozef Baranec, Co-Founder & CEO of PDFix. “By integrating callas pdfaPilot technology we were able to deliver reliable font fixes within months and focus our own development on accessibility workflows and automation.”

This decision changed the trajectory of the project in two important ways. First, it provided access to proven, production-ready PDF technology to resolve complex font challenges quickly and reliably. Second, it removed the need to develop and maintain highly specialized font handling internally – a task that requires continuous updates and deep knowledge of the PDF specification.

Within the PDFix platform, callas technology is used to resolve complex font problems, including embedding missing fonts, ensuring correct Unicode mappings (ToUnicode tables), and repairing font structures and text-to-Unicode relationships within the PDF. These capabilities complement the accessibility validation and remediation features developed directly by PDFix.

Flexible, Modular Automation

To support scalable processing, PDFix built a modular architecture based on containerized execution. Automation actions are packaged as Docker containers, allowing functionality to be developed once and deployed consistently across different environments.

This approach enables:

• fast deployment of new features
• consistent behavior across platforms
• flexible combination of processing steps

Examples of automation actions include:

• HTML-to-PDF conversion using headless browsers
• font correction using callas pdfaPilot
• offline language detection using local AI models
• optional integration with online AI services

Importantly, this architecture supports local processing, allowing organizations to keep documents within their own environment – a key requirement for many customers. The pdfaPilot technology natively supports Linux and containerized environments, making it a natural fit for this architecture.

Processing at Scale: A Real-World Example

The impact of this approach becomes clear in large-scale projects. An example is the Judicial Council of California, which needed to process a very large archive of documents to meet accessibility requirements. The initial phase alone involved approximately 200,000 documents, all within a limited timeframe, followed by ongoing remediation of newly created content.

By combining PDFix accessibility technology with callas font correction capabilities, it became possible to process this volume efficiently and reliably. What would otherwise have required extensive manual effort was transformed into an automated workflow. Accessibility was no longer a bottleneck – it became a scalable, repeatable process.

Jozef explains further: “Many of our customers need to process large volumes of documents and achieve clear accessibility validation results. By combining PDFix automation with callas technology for complex PDF fixes, we can deliver reliable remediation workflows that scale from individual documents to hundreds of thousands of files.”

From Complexity to Confidence

For organizations dealing with accessibility requirements, the goal is simple: documents that pass validation and meet compliance standards.

By combining deep accessibility expertise with proven PDF technology, PDFix enables customers to move from complex, error-prone processes to reliable, automated workflows.

The result is not just technical compliance – but the ability to deliver accessibility reliably, at scale.