To check your eBook for accessibility and formatting issues, we recommend using two separate tools:
✅ ACE by DAISY – This tool checks whether your EPUB meets accessibility standards (such as WCAG and EPUB Accessibility 1.1). It highlights areas like missing alt text, navigation structure, and more.
✅ EPUBCheck – This tool verifies the technical integrity of your EPUB file. It ensures that the file is structured correctly and meets the requirements set by most major retailers.
Heads up: These tools currently work independently. While ACE checks accessibility and EPUBCheck handles technical validation, the two don’t always align. In some cases, changes made to improve accessibility may cause EPUBCheck to flag errors.
This is a known issue across the industry, and updates are expected in the future to improve compatibility between accessibility and validation standards.
For now, we recommend running your file through both tools and aiming for a balance: meet accessibility best practices where possible, while ensuring your EPUB still passes EPUBCheck to avoid publishing issues.