EPUB accessibility checker
The checks Ace runs on an EPUB's markup and metadata, on a file you drop here. Nothing leaves your browser.
What the findings mean
- metadata-accessmode, metadata-accessibilityfeature, metadata-accessibilityhazard
- The package file does not say how the book can be read, what it offers, or what it might trigger. Required. Your formatting tool writes these; if they are missing, it did not.
- epub-type-has-matching-role
- An element is marked as a chapter, a footnote or a note reference for the reading system, but carries no matching ARIA role for a screen reader. The tool that built the file has to add it.
- epub-toc-order
- A table of contents entry points at nothing, or the entries are not in reading order.
- image-alt
- An image has no alt attribute at all. An empty one marks a decorative image and passes; a missing one fails. Add a description in your manuscript and export again.
- heading-order
- A heading level is skipped: level 3 after level 1. Usually a subheading styled as Heading 3 in Word. Change its level.
- td-has-header
- A table of three by three cells or more has data cells with no header row or column. Mark the first row as a header row.
- html-has-lang, document-title
- A chapter file with no language or no title. Set the book's language in your formatting tool; the title comes from the chapter's.
The full list of rules, and what each one asks, is in Ace, the EPUB accessibility checker: what it tests and how to pass.
Questions
- What does this check?
- The rules Ace, the DAISY Consortium's EPUB accessibility checker, applies to a file's markup and metadata: the required accessibility metadata and its allowed values, the table of contents and its order, the ARIA role on every structural element, images without alt text, headings that skip a level, tables without headers, links without a name, document titles and languages. Every finding carries Ace's own rule id.
- What does it not check?
- Anything that needs a rendered page: colour contrast, link colour against the surrounding text, whether a paragraph is styled to look like a heading. Ace decides those by running a browser over each chapter. A clean result here means the file's markup and metadata pass; run Ace itself, or read the book, for the rest.
- Is my file uploaded?
- No. The file is opened and checked in your browser. Nothing is sent to a server, stored or logged. You can disconnect from the internet after the page loads.
- Why does a distributor run Ace?
- The European Accessibility Act requires ebooks sold in the EU to be accessible, and the EPUB Accessibility specification it points to has Ace as its reference checker. Distributors and library suppliers run it on incoming files and send back the ones with critical or serious findings.
- What do the severities mean?
- Ace's own four: critical, serious, moderate and minor. A file with critical or serious findings is one a reviewer sends back. Moderate and minor findings are reported and usually tolerated.
- My file has no findings. Is it accessible?
- Its markup and metadata are. Whether it is accessible also depends on things no checker reads: whether the alt text describes the picture, whether the reading order makes sense. If every picture has a real description and the headings match the book's structure, the file is what publishers mean by an accessible ebook.
Writing a book?
Nueel runs this check on every EPUB it writes, lists the findings only you can fix before the file exists, and declares conformance in the file when it passes. $139 once, in your browser.