As far as I know, there is no such thing as an ePub viewer that completely implements the current ePub 3.2 standard. For example, other than a rumored custom ePub viewer made for Japanese schools, phonetic markup does not seem to be implemented by any of them.
Please note that ePub viewers designed for ePub 2 usually work fairly well with ePub 3.2 content though some features may not be available and SVG features often are often only partially supported in those viewers. Most books do not use any SVG, but for academic works with figures it really is necessary.
If you already have a digital book viewer you enjoy and it supports ePub, that is probably the best choice for you unless SVG does not render correctly.
If you are looking for suggestions, the following ePub viewers are what I recommend:
My only experience with a hardware eBook viewer is the Kobo Clara HD (available from Walmart) and it is a wonderful device. As long as what you are reading does not need color or audio, the eInk screens are the best experience for both avoiding eye fatigue and glare. Furthermore, the battery lasts a very long time between charges.
For proper ePub 3.2 support, the filename of the ePub must end with
.kepub.epub. Otherwise the Kobo will render it using the ePub 2 engine and some SVG will not work properly. Pipfrosch Press always uses that extension by default.
The Kobo does not support the ePub 3.2 ‘Landmark’ navigation or navigating to the start of a particular page in the print version of a book.
To get an ePub onto a Kobo device, you need to do what is called sideloading. Basically you plug the USB cable into a computer and copy the file from the computer to the Kobo.
In the future when Pipfrosch Press has a decently sized catalog, I may attempt to get the catalog into the Kobo store where they can either be downloaded directly for free or for as cheap as the Kobo eBook store allows, but for now side-loading is the only option.
I really love my Kobo. Reading on it really is better than reading on other devices.
First of all, I recommend against using the Google Play Books application. It copies the digital book to the cloud and then serves it back to your device over the Internet. When you do not mind Google knowing what books you are currently reading and how often, that actually is a very nice feature—when it works. I have had a lot of problems using Google Play Books with all but the simplest ePub content. I hope they fix these issues in the future, cloud storage for the library is a very attractive feature for many users.
Lithium EPUB Reader
Available from the Play Store: Lithium: EPUB Reader
This is my personal favorite ePub viewer on Android. I did pay for the premium version (inexpensive upgrade), but even the free version does not contain third party advertisements and I really appreciate that. It does not support some features like the ePub 3.2 ‘Landmark’ navigation but for me, it just feels the best. This is the Android viewer I test the most with.
Available from the Play Store: Kobo Books
This is the Android counterpart to the Kobo hardware eInk readers. Use of the application does require an account with Rakuten (free). It does support both color and audio content, but other than that, it is very much like the hardware device in rendering content. With books purchased from Kobo it does keep in sync with both the hardware device and other installs of the Kobo Books reader on Android and Apple platforms, this is nice because you can pick up where you left of reading one device on another device. It does not seem to offer this feature for content that was not purchased from Kobo.
If you use Kobo already and like it, this reader does very well with ePub 3.2 content as long as the file name ends with
.kepub.epub. Pipfrosch Press always uses that extension by default.
Available from the Play Store: R2 Reader
As far as technical features are concerned, this is probably the most advanced ePub viewer for Android. For example, this is the only one I have found so far that implements navigation by the equivalent page in the print version of a book or article. This also is the only Android reader I have found that supports OPDS. Pipfrosch Press does not currently make use of OPDS but we plan to in the future. This reader also can read the content to you but I found the speed to be a bit too fast and did not see an obvious way to slow it down. There probably is a way to slow it down, but I could not find it.
The interface feels a bit clunky. I like this reader and I suspect over time the interface will vastly improve, but personally I prefer the interface of Lithium.
Moon+ Reader Pro
Available from the Play Store: Moon+ Reader Pro
This is the favorite for most Android consumers of ePub content I have communicated with. There also is a free version, I have not tried the free version.
This is a very nice reader if you want to have the content read to you. With academic content, some of the more technical terms will be incorrectly pronounced, but it actually does a fairly decent job. Unfortunately it does not do a very good job at rendering SVG content which is why I have it listed last. My suspicion is this reader uses Adobe Digital Editions underneath and has not been updated for the ePub 3 standard.
My experience with Apple mobile platforms is admittedly very limited to an older 3rd generation iPad (no longer supported by Apple) and occasional access to a iPhone 7s that is not mine so I can not install apps for testing.
Ships on older iOS devices. Actually works very well with Pipfrosch Press content, I like it.
With audio and video content, it crashes if captions or subtitles are enabled but it does not support the Ogg Opus audio that Pipfrosch Press will sometimes use in the future so that is not an issue.
Ships on recent versions of iOS and iPadOS devices. Works very well with Pipfrosch Press content although the cover image seems to sometimes vanish from the library.
This only happens in Apple Books and may be because Apple requires some special non-standard tag within the ePub, like they do to use fonts provided with the ePub instead of their own fonts.
I will investigate this at some point when I have better access to Apple Books.
Basically, Apple forked the ePub 3 standard to create their own proprietary standard that requires their authoring tools to publish in. It is part of a strategy called ‘Embrace, Extend, Extinguish’ that tech companies sometimes use when they want to destroy an existing open platform so that their proprietary platform has monopoly status. It is a very anti-consumer strategy but is a very capitalist strategy.
Apple still supports ePub content but often requires non-standard tweaks in order to get standard functionality, such as the use of embedded fonts. Something similar may be what is going on with the cover images for Pipfrosch Press publications and why they vanish from view from the library in my limited testing (though the books remain and can be read).
The cover image is not an issue in the older iBooks or any other ePub viewer I have tried.
Available from the Apple App Store: Kobo Books
This is the only ePub viewer I have found that actually still provides updates for the version of iOS running on my third generation iPad. The notes for Kobo Books on Android apply.
For those of us who still use an actual computer rather than a so-called ‘smart’ device there are a couple options that run on every modern operating system and one option that only runs on macOS.
Available from EDRLab: Thorium Reader
This is by far the most advanced and best ePub viewer I have used on any platform. It has full support for both ‘Landmark’ navigation as well as navigation to a specific page equivalent in the print published version of the book or article.
Thorium also properly integrates with Narrator, NVDA, JAWS, and VoiceOver for users who are print-disabled. Thorium was also built with dyslexia in mind for users who are not print-disabled but do have some vision related access barriers.
On GNU/Linux systems if Thorium is not packaged for your particular distribution, installation can be a bit tricky and my experience on CentOS 7 is that it can be slow to launch, but it is the best ePub viewer I have ever used once it has launched.
Thorium Reader also supports OPDS. Pipfrosch Press does not currently make use of OPDS but we plan to in the future.
Available from calibre-ebook.com
Calibre is not just an ePub viewer, it also can be used to manage an eBook library and sync it with mobile devices, to convert eBook content from one format to another, and to author ePub content.
I have not used it to sync an ePub library. My brief attempts to convert from ePub 3 content to the Mobipocket (
.mobi) format that allegedly works on Kindle devices were only successful for basic content. The ePub authoring features I found to be too limiting. Their authoring tool also gives false errors about perfectly valid font MIME types.
The viewer is however a decent viewer, although it lacks a lot of modern features. This viewer is the viewer used to test Pipfrosch Press content during development.
The really nice thing about the viewer is that it does not insist upon importing the ePub into its library to render it, and this allows me to keep one version open, make some tweaks and rebuild, and view the tweaks in a separate window next to the open window for visual comparison. This is much more difficult with readers that insist upon importing an ePub into the library before rendering.
On the macOS platform, Apple Books is already installed. I have not done any testing with it, I will try to within a week (by Friday, May 22 2020).