#1216: WG Revision: EPUB 3.4

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Opened Apr 2, 2026

Specification

https://www.w3.org/TR/epub-34/

Explainer

https://w3c.github.io/epub-specs/epub34/overview/

Links

The specification

Where and by whom is the work is being done?

  • GitHub repo: https://github.com/w3c/epub-specs/
  • Primary contacts:
    • Toshiaki Koike (@toshiakikoike), Voyager Japan
    • Wendy Reid (@reidmore-online), W3C Invited Expert
    • Brady Duga (@bduga), W3C Invited Expert
    • Gautier Chomel (@gautierchomel), EDRLab
  • Organization/project driving the specification: W3C EPUB Working Group

Feedback so far

EPUB 3.3 was previously reviewed and signed off by the TAG in #684 and #816. This new version, EPUB 3.4, is a maintenance update. Key changes based on previous feedback and WG consensus:

  • Simplification:
    • We removed several under-utilized attributes (primarily related to layout) that were often ignored by Reading Systems to better align with actual user-controlled experiences.
    • Dropped font obfuscation, which had been criticized in previous reviews.
  • Architecture:
    • Emphasis on the layered security model: EPUB inherits security from W3C Web standards and leverages the security features of modern WebViews used in Reading Systems.

You should also know that...

Key new features include:

  • Roll Layout: Introduction of roll layout support, enabling "Webtoons" and similar vertical-scroll content within EPUB.
  • Annotation Exchange: Support for exchanging annotations between Reading Systems (Note: This specific feature is currently in First Public Working Draft and will be subject to a separate, more detailed TAG review later).

Other improvements:

  • Accessibility and Standards: Further refinements for accessibility and improved alignment with modern Web Platform standards.

We have prioritized backward compatibility and ensured there are no breaking changes to the Web architecture.

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Track conversations at https://tag-github-bot.w3.org/gh/w3ctag/design-reviews/1216

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