EPUB Accessibility Metadata Lint (EAA)

Open an EPUB package file (.opf) and this extension reads the accessibility metadata the way an EU bookseller's ingest script reads it: literally.

Since 28 June 2025 the European Accessibility Act (Directive (EU) 2019/882) covers e-books, and the accessibility information has to travel inside the publication's metadata, not in an email to the retailer. EPUB Accessibility 1.1 (W3C Recommendation, 2023) is the standard that defines which properties carry it and what the conformance string looks like. Both are unforgiving about spelling: altText is not alternativeText, and WCAG 2.2 AA is not WCAG 2.2 Level AA. A value outside the vocabulary is not a smaller claim, it is no claim at all — the ingest drops it.

What it does

EPUB A11y: Check this .opf runs 18 rules over the open file and reports every finding on its own line, with the exact replacement line to paste:

• schema:accessMode, schema:accessModeSufficient — present, and every value inside the vocabulary (accessModeSufficient allows only auditory, tactile, textual, visual)
• schema:accessibilityFeature — present, spelled as schema.org spells it, and not none sitting next to a list of features
• schema:accessibilityHazard — present, including when the answer is none
• schema:accessibilitySummary — present, and a real sentence rather than "This ebook is accessible."
• dcterms:conformsTo — one of the strings EPUB Accessibility 1.1 defines, and flagged when it still claims the superseded 1.0
• a11y:certifiedBy — required whenever a conformance claim is made
• Print page numbers declared with no dc:source for the print edition
• EPUB 2 name/content metadata that an EPUB 3 reader never looks at
• A textual alone claim over visual content with no alternative-text feature: a claim that cannot be true

The sample file

_fixtures/dirty.opf is the kind of package a generative assistant writes when you ask it for "accessibility metadata": confident, well indented, and wrong. The extension reports 12 findings in it — 9 errors and 3 warnings — of which 6 are invented or malformed values (altText, screenReaderFriendly, sight, screenReader, noFlashing, and a conformance string missing the word Level). _fixtures/clean.opf is the same book after the fixes: 0 findings.

Free, and the part that is not

Checking the file you have open is free and finishes the job: every finding, every fix line, no key, no limit on how many files you open. The paid layer is a different axis — scope and a document you keep: EPUB A11y: Sweep this folder walks every .opf in the workspace in one run and writes a dated pass/fail report per title, the thing a distributor or a retailer asks you for.

Full version (folder sweep and the dated report): https://buy.polar.sh/polar_cl_oPMAjVdCsJ3pQdXfabWNj50DOpyh2wFYTMd6w11o7Aj

Yardstick

An EPUB production freelancer bills $50 to $95 an hour.

Hub and the free web version: https://getreadystack.com/tools/epub-a11y-metadata-lint

Commands

• EPUB A11y: Check this .opf — lint the active file (free)
• EPUB A11y: Sweep this folder — every .opf in the workspace, dated report
• EPUB A11y: Enter licence key

Licence and refund

$29 once, one licence key per person or team seat, 7-day full refund. The key is validated against the Polar customer portal; no account and no telemetry.

Not legal advice. It reads metadata and reports what the standard says; the conformance claim is still yours to make.