Original Readium Development Kit
This is the original project of the Readium Foundation, a community in which EDRLab plays a large part since its creation in 2015. It is split is two parts, ReadiumJS and Readium SDK.
What is ReadiumJS?
Readium JS will be replaced by the end of 2021 by Readium Web.
A Readium Chrome Application has also been built from ReadiumJS. It is one of the most full-featured EPUB 3 Reading Systems available, but Google has decided to deprecate all Chrome Applications, therefore it will stop running on Chrome someday (as of April 2021, it is still available on the Chrome Web Store). It is now replaced by Thorium Reader.
The source code for both the Chrome Application and the CloudReader is available under a BSD-type open source license. It can be downloaded from the Readium Github and modified to suit specific needs.
More information about ReadiumJS can be found on the Readium documentation website.
What is Readium SDK?
It comes along with iOS and Android testing wrappers, called “launchers”.
Since 2018 and version 0.30, the project is released with a BSD-type license, which allows the use of the SDK in both open and closed-source for free.
The SDK has been included in several reading applications on iOS and Android; a partial listing is found here.
What is the development status of Readium SDK & JS?
The release history is maintained on the Readium documentation website.
Since March 2018, the stable version of Readium (both SDK and JS) is 0.30.
The project is now mature and stable, it is not maintained anymore by the Readium community which concentrates on Readium Mobile, Readium Desktop and Readium Web instead.
Other Readium projects
The vendor-neutral and interoperableDigital Rights Management technology, embeddable in any reading application based on the Readium SDK.