Modern EPUB 3 Reading Systems
One of the assumptions I'm making with the SEED.html app and the content it produces is that the underlying rendering software for EPUB 3 will be based on web standards and provide modern CSS and JavaScript features.
Here's what I know of the current state of EPUB Reading Systems that support the kind of content I'm exploring. They are phone/tablet apps that are based on some version of WebKit, likely provided via the Readium stack.
First up, on desktop (macOS, Windows and Linux) there is good work being done on the Thorium Reader app by the European Digital Reading Lab (EDRLab).
As far as I can tell it's used by a couple of applications that I recommend here.
| Platform | App Name | Download link | 'scripted' | OPDS |
|---|---|---|---|---|
| iOS, Android | Cantook by Aldiko | Google Play Store Apple App Store |
️✅ | ️✅ |
| Windows, Linux, macOS | Thorium Reader | EDRLab | ️✅ | ️✅ |
| macOS, iOS | Books | Apple Books | ️✅ | ❌ |
| Android, iOS | Lis-a | Google Play Store Apple App Store |
️✅ | ❌ |
| Android | (Google Play Books) | Google Play Store | ❌ | ❌ |
Scripted support
Special mention for Google Play Books, which uses a modern webkit-based renderer, but has no way to enable support for scripted content, so it's of little interest when discussing interactive EPUB 3 content.
(I'm also not fond of being forced to upload content to the Google cloud just to get it into the app, so I spend no time looking at this app and mention only because it's from Google and installed by default on the Android devices I have seen.)
There are a few other apps on Android (Reasily, BookFusion, Ebook Reader) that do the job, but the above list includes the ones I have an eye on.
OPDS support
EPUB Reading System capabilities
In support of this content creation process I have a 'Diagnostic EPUB' that I load into each app to quickly confirm its capabilities.
It contains a set of largely script-driven checks for CSS, SVG and web API support.
I hope it becomes increasingly useful for EPUB designers and developers as more reader apps are built on the web stack.