David Herr

PDF Accessibility Remediation Software Tools: A Detailed Comparison

For many years, there have only been two tools for PDF remediation for accessibility available in the market. Adobe Acrobat Pro DC was the original tool for adding tags and editing the tags for accessibility compliance. CommonLook PDF enhances Acrobat’s deficiencies and provides the only comprehensive one-stop-shop for ensuring that documents are fully accessible and standards-compliant.

Since then, however, the ever-increasing demand for compliant digital files has brought new tools to the market, claiming to make it easier to create accessible documents.

So, do they deliver on their promises? What are the differences between those tools?

This article will help you decide your best solution for guaranteed compliant and accessible documents.

Let’s start at the beginning and talk about the traditional method of achieving fully accessible and standards-compliant documents.

Document Accessibility Methodology – Adobe and CommonLook

The first step to PDF accessibility-but not the only step-is a tagged PDF. Let’s define what PDF tags do and why they are essential for accessibility.

When a PDF is tagged, you can review the Tag tree through the Tags panel, a separate view of the document accessed through View > Show/Hide > Navigation Panels > Tags. The tags identify content information and attributes.

There are many different types of tags used to describe the content, including Headings, Paragraphs, Lists, Figures, Tables etc. Note that the Tag tree does not affect or change the visual appearance of the document.

The purpose of the Tag tree is to work with screen readers and other assistive technology to allow the content to be fully accessible. The Tag tree also provides for navigation of the document. For example, PDF files with the correct tagging for headings allow a screen reader user to navigate a document, much like a sighted reader would use the Bookmarks, or a Table of Contents, to search for the information they are trying to find in the document.

The tags contain attributes as well; as an example, a Figure tag for an image would have the Alt-text or Alternative text description of the image that would be read by a screen reader for the image selected.

Standards organizations such as the W3C and the ISO have created standards for document accessibility to ensure the tagging is done correctly, such as WCAG 2.1 and PDF/UA.

Documents tagged to meet the standards are your best assurance of full accessibility and reduce legal risks due to non-compliance.

By now, you know that an accessible document is an accurately tagged document. Therefore, it’s critical to verify correct tag usage. In addition, the reading order may need to be adjusted, images must have Alt-text descriptions, and remediators should check for proper navigation heading levels.

PDFs created using Acrobat, or another source are not usually tagged by default. However, Acrobat has an Accessibility tool with the option to Autotag Document, which will add the Tag tree and attempt to determine the correct tags for the content.

The Adobe process for creating accessible documents is to review the tags that were made, ensuring that proper heading levels, paragraphs, tables, lists, figures and other content are correctly tagged. In addition, the tool has a function called Accessibility Check, which reviews the document and Tag tree for common accessibility issues. You can then review the list of items identified and make the corrections to fix any discovered issues.

Review of Accessibility Software for Creating Accessible PDF Documents

Acrobat Pro DC

Acrobat Pro DC Pros

  • Working in the Tag tree helps achieve a fully accessible document because manual checks are necessary, like verifying appropriate alt text.
  • Allows for the creation of tags, even from an untagged document.
  • Correct reading order.
  • Create and/or convert tags.
  • Add alternative text to tags.
  • Set the tab order.
  • Can correct (some) color and/or contrast issues.
  • Add/Edit Metadata including Title and Language (required by standards).

Acrobat Pro DC Cons

  • Passing Acrobat’s Accessibility Check does not guarantee compliance with any accessibility standards (WCAG 2.0/2.1 or PDF/UA), and there are often many remaining accessibility issues to be fixed.
  • Accessibility Check only tests checkpoints that can be verified with automation. There are a couple of prompts for the tester to check things that require manual validation.
  • You will need a third-party testing tool like CommonLook’s PDF Validator or PAC3 to verify standards compliance.
  • Many tasks in Acrobat in working with the Tag tree are complex and time-consuming.
  • Without an “undo” feature, you may be forced to start over if you make a mistake.
  • Remediating data tables is a lengthy, inefficient and time-consuming process.
  • Assigning ListNumbering to lists is challenging.

CommonLook PDF

For years, CommonLook PDF has been the go-to tool for professional document remediation. CL PDF works in conjunction with Adobe Acrobat Pro DC to be an “all in one” to test, remediate and verify PDF documents to the standards.

Unlike other solutions, you do not need to use multiple tools to do your testing. You can fully remediate and test documents in the CL PDF toolset without leaving the program. Unlike Adobe Acrobat Pro DC, CommonLook has a proven workflow that allows for 100% compliance.

  1. Tag the document in Acrobat (if the document is untagged).
  2. Run CommonLook PDF.
  3. Open the Tag Tree.
  4. Remediate the document.
    1. Artifact images as needed (images that do not convey relevant information).
    2. Verify reading order.
    3. Verify correct tag usage.
    4. Look for color issues.
    5. Fix tagging errors including tables, forms, links, artifact headers/footers using the tools and wizards provided.
    6. Set the tabbing order to follow the document structure.
    7. Add the Document Tag.
      1. Add Bookmarks.
    8. Clean up empty tags (using the included wizard).
      1. Add Metadata information (adding the checkbox for 508, WCAG, PDF/UA or HHS.
    9. Run CommonLook Verification on both structural and accessibility compliance.
    10. Generate and save the CommonLook Accessibility Report according to the chosen standard (WCAG2.1AA, PDF/UA/HHS/508).

As you can see, using our process is thorough and designed to check that all aspects of document accessibility are covered so that you can achieve PDF accessibility and compliance with a matching accessibility report.

CommonLook PDF Pros

  • Provides validation against Section 508, WCAG 2.0, WCAG 2.1, HHS and PDF/UA standards, and ISO 32000-1:2008.
  • Validation includes those checkpoints that require manual verification, ensuring 100% accuracy.
  • Time-saving tools for working with the Tag tree.
  • Automatically tag tables, lists and Table of Contents from selection.
  • The table editor tool makes complex tables easy to tag correctly.
  • Easily assign the ListNumbering attribute for lists.
  • Supports difficult to tag content such as multi-page structures and structures that move between pages.
  • Automatically detects and repairs a variety of common PDF problems.
  • Much faster than Adobe Acrobat Pro DC.
  • Generates a checkpoint-by-checkpoint report that many organizations accept as proof of accessibility compliance.

CommonLook PDF Cons

  • Currently only available for PC users. (Mac users can get around this by using Parallels)
  • Cannot automatically add tags to an untagged PDF (CommonLook PDF, as an Acrobat Plug-in, works with the Acrobat built-in autotagging features to ensure 100% compliance.)
  • Only one PDF can be opened at a time

There are three other tools for creating accessible PDF documents. One of them is an autotagger which does not work directly with the Tag tree but attempts to tag the documents based on user input. Note: this function is available for free with Adobe Acrobat Pro DC.

The other available tools are better suited for touch-ups because their purpose is to clean up the tags in a document, but they do not address all the requirements. Additional work and tools are required to complete the tagging, remediation, and verification process.


axesPDF is a touch-up and test tool that provides limited functionality in remediating some accessibility issues.

Our review of the tool discovered that while it has some useful features, you would still need to use several other tools to ensure the tags are correct and verify full 100% compliance with the accessibility standards.

axesPDF Pros

  • Standalone application
  • Tests against PDF/UA
  • Fixes font and Unicode issues
  • Screenreader preview
  • Displays the Tags tree (Logical Structure Tree)
  • Multiple PDFs can be open while working

axesPDF Cons

  • Limited remediation functionality – relies on mostly-correct tagging structure to then address PDF/UA-specific requirements
  • Tagging functionality is limited to touch up and fixing limited issues.
  • No Undo
  • The software is not fully keyboard-accessible.
  • The user interface does not feel “intuitive.”
  • It only tests checkpoints that can be tested with automation. So, for example, while the checker will detect Figure tags without Alternative text and show that “Failure,” any Figure tag with Alternative text will automatically pass even if the alt text is inaccurate.
  • Does not test against either of the WCAG standards or others.
  • Delete empty tags removes *all* empty tags, possibly affecting table tagging

AccessibilityNow® Remediate

Crawford Technologies describes its tool as an “ad hoc tagging tool” designed to tag documents or do the final steps in an already tagged PDF document. The tool will function standalone without needing Adobe Acrobat and can either add tags or be used to do tag finishing.

The visual interface automatically senses tagging elements and assigns tags to the content. The graphical interface allows the user to verify that the tags are correct, including reading order, paragraphs, heading levels, lists, tables and URLs. However, they do not claim that the resulting files meet 100% compliance with the common standards. There is a similar feature within Adobe Acrobat at no cost.

AccessibilityNow® Remediate Pros

  • Requires less knowledge of accessibility or the Tag tree since you rely on the tool to identify the proper tags.

AccessibilityNow® Remediate Cons

  • The product promises to deliver accessible PDF documents but does not provide compliance reports for any of the common accessibility standards (508, WCAG 2.0, 2.1, HHS or PDF/UA), which could result in a non-compliant and inaccessible document.
  • Without the ability to test and validate the documents against the standards, you will need additional tools to confirm compliance with the standards.
  • PC only.
  • While it identifies tags, you are trusting the tool to get it right, so there is a greater chance of error using this method of document tagging. Acrobat autotagging generally does a better job in most cases.


Onix advertises Equidox as a “cloud-based PDF remediation software solution that converts inaccessible PDF documents into WCAG 2.0 AA compliant HTML and accessible PDF”. It is also an autotagger that uses its smart detection tools to determine how the document should be tagged. Note: the autotagging feature is free within Adobe Acrobat.

Tools like Acrobat Pro DC and CommonLook can provide 100% compliance with the standards since you directly manipulate the Tag tree. Still, this tool relies on the user to use a visual interface to verify heading levels, reading order and similar content. Equidox then attempts to tag the content using automation technology.

Equidox Pros

  • It does not require knowledge of accessibility or the Tag tree since you are not working with the actual tags in the document.

Equidox Cons

  • As with AccessibilityNow® Remediate, you are trusting that the tool will get it right, so there is a better chance of error using this method of tagging the document.
  • It does not tag PDF files to the standards and does not provide a compliance report.
  • Onix describes Equidox as “Accessible PDF Conversion”, and they recommend converting PDF to HTML. But, unfortunately, converting PDF to HTML is not an option for many organizations.


While there are several PDF Remediation tools on the market, CommonLook PDF has the most complete set of features, making it the only choice if you need a verified solution that offers comprehensive and documented compliance to a specific standard. As a result, it is the professional remediator’s tool of choice.