Yes — you can check whether your EPUB meets current accessibility expectations yourself, for free, using Ace by DAISY, the open-source EPUB accessibility checker built by the DAISY Consortium and run from a command line or its desktop app, at no cost and with no account required (per the DAISY Consortium's documentation).
| Tool | Maker | Price | Key specs | Release date | Basis of coverage |
|---|---|---|---|---|---|
| Ace by DAISY | DAISY Consortium | Free, open source | Command-line and desktop app; HTML report on violations, metadata, outlines, and images | CLI: January 2018 · Ace App (GUI): summer 2019 | DAISY Consortium documentation and W3C's EPUB Accessibility–EAA mapping note (August 28, 2025) |
Why does this matter to indie authors now?
The European Accessibility Act is an EU directive that member states had to incorporate into national law by June 2022, and it explicitly lists e-books among the covered products and services, per the European Commission's overview page. The Commission's page notes it monitors "the complete and correct implementation and transposition of the Act" through national authorities rather than spelling out penalties itself. Separately, a W3C Group Note published August 28, 2025 confirms the EAA is enforceable from June 28, 2025, and demonstrates that the existing EPUB Accessibility 1.1 standard already satisfies the directive's technical requirements for e-books — meaning authors don't need a new format, just conformance to a standard that already exists.
What the sources here do not establish is how enforcement reaches an individual self-published author selling outside a major EU-facing retailer, or what a non-EU-based author's exposure looks like. Treat that as an open question for your own platform's policies, not something this piece resolves.
What does an EPUB accessibility checker actually test?
Ace runs automated tests against an EPUB's content documents, with particular focus on violations, metadata, document outlines, and images, per the DAISY Consortium's documentation. It doesn't read your prose for quality — it checks structural and technical markers: whether images carry alternative text, whether headings form a sensible outline, whether metadata declares the accessibility features actually present.
Underneath that automated check sits a mapping to real standards. W3C's EPUB Accessibility–EAA mapping note cross-references specific WCAG 2 success criteria against EAA requirements — for example, it notes that presenting information through more than one sensory channel is satisfied by WCAG Success Criterion 1.1.1, Non-text Content, at Level A. That mapping is also what covers assistive-technology compatibility, navigation structures, and DRM guidance meant to preserve accessibility features rather than block them.
How do you actually run the check?
Per the DAISY Consortium's documentation, there are two ways in:
- The command-line tool, first released in January 2018, suited to authors or formatters comfortable scripting a check into a production workflow.
- The Ace App, a desktop graphical version released in summer 2019, aimed at anyone who'd rather point the tool at a file than a terminal.
Both versions produce the same kind of output: an HTML report built around violations, metadata, document outlines, and images, per the DAISY documentation. That report is the artifact worth keeping — it's what you'd hand to a formatter or a proofreading pass to fix, and it's dated evidence that you checked, if a retailer or distributor ever asks.
What the checker's finding areas map to
| What Ace flags | What it's checking against |
|---|---|
| Images without alt text | WCAG 2 Success Criterion 1.1.1, Non-text Content (Level A), per W3C's mapping note |
| Document outline and navigation | EPUB Accessibility 1.1's navigation structure requirements, per W3C's mapping note |
| Accessibility metadata | Discoverability requirements under EPUB Accessibility 1.1, per W3C's mapping note |
| DRM handling | EAA guidance that DRM must preserve, not block, accessibility features, per W3C's mapping note |
What can't the checker do for you?
Automated testing has a documented ceiling. W3C's mapping note itself flags technical limitations for fixed-layout publications — comics and illustrated children's books among them — around text resizing and formatting flexibility, meaning some accessibility properties in those formats can't be fully automated or fully achieved the way they can in reflowable text. A clean Ace report on a fixed-layout file doesn't mean every accessibility expectation has been met; it means the automated checks that can run on that format have passed.
The report also won't judge whether your alt text is actually useful, only whether it exists. Writing alt text that describes what an image communicates, not just that it's present, is a human judgment call the tool doesn't make for you.
Does a passing report mean your book is compliant?
Not on its own. Per W3C's mapping note, the EAA's e-book requirements are satisfied by full conformance to EPUB Accessibility 1.1, which spans more ground than what one automated tool flags — including synchronized audio-text support and assistive-technology compatibility that need real testing, not just a structural scan. Treat a clean Ace report as a strong, free first pass, not a final signature.
FAQ
- Does the European Accessibility Act apply to authors selling outside the EU? The sources reviewed here don't establish this directly — the European Commission's page addresses EU implementation and monitoring, not the exposure of a non-EU-based, EU-facing seller specifically. Check your distributor's own compliance guidance for that answer.
- What happens if my EPUB fails the Ace report? The HTML report lists specific violations by category — images, metadata, outlines — for you or a formatter to fix and re-run, per the DAISY Consortium's documentation; it doesn't itself issue a pass/fail compliance verdict.
- Does Ace check fixed-layout EPUBs the same way as reflowable ones? No. Per W3C's mapping note, fixed-layout formats such as comics and illustrated children's books carry technical limitations around text resizing and formatting flexibility that reflowable EPUBs don't share.
- Is Ace by DAISY free to use? Yes — per the DAISY Consortium's documentation, both the command-line tool and the Ace App are free and open source, with no account required.
For a related devices perspective, read What EPUB Accessibility Actually Requires, and Why It Matters.