Epub is a format familiar to e-book readers. Most e-books have the extension of epub and it is widely recognized on a variety of devices. Epub contains mostly books filled with only text but newer versions of epub now include images as well. Internet Archive has two versions of epub:
- Epub format of books that are added to the archives by the user
- Or copies of books scanned as images. These books contain pages of the original book
The Internet Archive adds books in the epub format directly or they are generated on the go. Books that are generated on the go are uploaded in the latest version of the epub code. Books that are uploaded directly as epub stubs have the code that was generated at the time of their creation. Due to a minor error, epub books generated after August 2015 do not function properly. These books were inaccessible across devices. The Internet Archive has reported that the errors in the codes of these books have been fixed and new epub books generated are working properly. The Internet Archive has also resolved to change the codes of the books that have been uploaded with faulty extensions. As the error has been identified, e-book readers can now be assured that the faulty books will be quickly replaced.