Fully conformant EPUB 3 support

Readium should implement 100% of the functionality required by the EPUB 3 specification. A number of features and behaviors are MIA from the initial proof-of-concept.

Support for all optional EPUB 3 functionality

Readium should implement all optional functionality defined by the EPUB 3 specification (the "shoulds" in addition to the "musts"), as well as implicitly optional features (e.g. JavaScript APIs such as XMLHTTPRequest and Geolocation that are separate specs from HTML5 so not normatively referenced by EPUB 3 specification).

Support for emerging EPUB features

Readium should be a testbed for newly proposed EPUB specifications such as fixed-layout metadata, CSS Page Templates,  dictionaries, indexes, etc.

Performance optimization

The initial proof-of-concept has to do things like unzipping in JavaScript. Optimization of this and other areas should be pursued.

Accessibility support

Screen-reader integration on Mac & Windows is top priority here.


Localization of Chrome Extensions is a well-defined process, so let's get Readium Chrome Extension for other languages. Once we have i18n framework set up, we could use non-technical help for creating UI strings.

Android configuration

Could be an entirely separate codebase from Chrome Extension configuration. Unlike Chrome Extension, could include a "fork" of WebKit to address issues at that level. Note that apps to be distributed via Android Market for smartphones and multi-purpose tablets may have quite different requirements than dedicated eReader devices based on Android (the latter may have significantly reduced performance, lower memory, e-ink display, etc.).

iOS configuration

Could be an entirely separate codebase from Chrome Extension configuration.  Needs to abide by Apple licensing restrictions against integrating a different WebKit than built-in to iOS, as well as against using private APIs.

Japanese typography

WebKit has some bugs and issues in Japanese typography. Readium should pursue addressing this, ideally getting fixes into WebKit itself. 

UX Refinement / User Features

While it's not a goal for Readium to be a production-level consumer Reading System we'd like to illustrate best practices and make the Chrome Extension and other configurations easy to use. Features to consider include:

  • Default font, font size, color
  • Day / night mode
  • Default margins
  • Default page transition (none, slide, curl, ...)
  • Disable JavaScript in EPUB
  • Drag & drop content into library view
  • register .epub file extension with system OS's so double-click opens in Chrome+Readium
  • preference setting or other way for user to control whether newly open EPUB files are automatically added to Readium library
  • integrated acquisition (e.g. OPDS support, built-in feeds to free content)

Chrome Extension specific feature support

Annotations/bookmarks support

Ideally based on EPUB 3 CFI spec, perhaps utilizing schema proposed by Adobe (compatible with Adobe Digital Editions). 

Additional developer-mode features

TBD to meet needs of content developers.

Content/app configuration

Using PhoneGap or similar framework, enable an EPUB publication plus Readium to be packaged into a book/app.