Accessibility is one of the major and unavoidable issues of the coming years for digital books (and the Web in general). In Canada, the Canada Book Fund has launched a funding plan which, firstly, aims to raise awareness of accessibility issues in the publishing world and, secondly, to support Canadian publishers in the production of accessible files (this part of the programme and the related grant applications have not yet been made public).
For its part, the European Union adopted a directive in 2019, according to which all books sold in the European Union will have to be accessible by 2025.

Accessibility can be found at several levels of the digital book chain:

  • The production of accessible digital books
  • The documentation of accessibility metadata by the publisher when he creates his publication with his distributor
  • The transmission of this accessibility metadata to booksellers
  • The management of this metadata by the booksellers to inform readers of the accessibility features included in each book
  • The management of this metadata by lending solutions to inform library users of the accessibility features included in each book

De Marque offers a service to produce accessible EPUB files. You can find more information about this service here: and contact us for a quote.

However, if you are producing your files in-house or dealing with another file producer, this document aims to provide you with a framework for producing your accessible EPUB files through guidelines and more in-depth resources on the subject.

General recommendations

Before we look in more detail at accessibility within a file, here are some general recommendations:

  • The reference format for an accessible file is EPUB 3 reflowable. It is strongly recommended that PDF and EPUB 2 be abandoned as much as possible in favour of the EPUB 3 reflowable format, as these formats do not provide the accessibility features necessary for people with visual impairments. The fixed layout EPUB 3 format also does not provide optimal accessibility, although it is a must for certain types of publications such as comics and photography books.
  • When designing a digital book, although it is normal to want to choose a layout that is close to the one chosen for paper, it is crucial to think about the experience of the final reader. In digital, reading comfort invariably depends on the chosen reading device (e-reader, tablet, phone, etc.) and its functionality. In order to guarantee an optimal reading experience on all media, it is sometimes necessary to detach oneself from the layout of the paper book, by following the following rules in particular:
    • Avoid images in the background of a title or text.
    • Avoid coloured backgrounds, or choose high-contrast colours that will stand out well on a reading machine (currently, colour is not yet supported by reading machines, so colours are rendered in greyscale).
    • For the same reason, if a colour is chosen for a font, again, it is recommended to use high contrast colours.
    • Avoid forcing a font, as reading tools offer different fonts. For example, most reading tools allow the reader to choose the OpenDyslexic font, which is specially designed to make it easier for dyslexics to identify letters. Forcing a font into the EPUB file prevents the reader from selecting the font that best suits their needs.
    • Use tags <ul> and <ol> for bulleted and numbered lists.
    • Avoid creating tables when the information can be rendered as text.
  • Overall, the most important question to ask when designing a layout for a digital book based on the layout of a paper book is to always ask yourself whether this layout is semantically relevant, or whether it is purely decorative, in which case it is important to make choices that are more suitable for digital reading.

Guidelines for producing an accessible EPUB 3 file

Here are the most important elements to consider when choosing to produce an accessible EPUB file:

  • Adjustable content: The content should be, as far as possible, adjustable by the reader (possibility to change the font, font size, margins, etc.).
  • Images: All images (except for decorative images) should be accompanied by a complete and relevant alternative text description. If you are using an external company to produce your files, the alternative descriptions should be provided to them at the same time as the source file that will be used to produce the EPUB version.
  • Language: The language of the text must be documented in each section to allow text-to-speech technologies to use the appropriate pronunciation.
  • Navigation:
    • The table of contents should be comprehensive and allow the reader to navigate easily through all sections and chapters of the book. It should also be included in the spine of the OPF document.
    • Footnotes and endnotes should be linked to the content to which they refer by means of internal links.
  • Content structure:
    • Each section of the EPUB file should be clearly identified using <section> and <epub:type> tags.
    • We recommend that ARIA roles are also included, as this gives even more semantic meaning to the different sections of the document.
    • The content must be structured correctly by respecting the different levels of hierarchy of sections and titles.
    • The addition of a pagelist (a list of the equivalent digital locations to the pages of the paper version) is highly recommended, especially in the case of content with a complex layout, as it helps the reader to find his or her way around the content more easily.
  • Accessibility metadata: The documentation of accessibility metadata within the book's OPF file, which allows computer systems and assistive technologies to quickly identify the accessibility features available in the book.

Resources available online

Standards and validation tools

Official reference documents

Here is the list of official reference documents issued by the W3C on accessibility:

Document that compiles all the rules and specifications related to accessibility within an EPUB file:
Document that describes the different ARIA roles and explains how to document them:
The Web Content Accessibility Guidelines (WCAG), available at

NNELS documents

Faced with the complexity of the official documents issued by the W3C, the NNELS (National Network for Equitable Library Service) has created a portal dedicated to accessibility, which includes reference documents aimed at making information more accessible to publishers.

The portal can be accessed via this link:

Resources for publishers can be found here:
The article Accessible Publishing Best Practices: Guidelines for Common EPUB Issues in Plain Language is particularly useful and can be accessed via this link:

File validation

In addition to the official EPUBCheck validator (fully integrated into our warehouse), we strongly recommend that you run your files through the Ace validator, developed by the Daisy consortium.

You can find more information about this validator here:
Please note that it is planned, in the long term (official date to be determined), to integrate this validator into our digital warehouse.