Wikipedia
Booktype
Booktype is a free and open source software for authoring, collaborating, editing, and publishing books to PDF, ePub, .mobi, and HTML formats. It was launched by Sourcefabric in February 2012 when Booktype evolved from the Booki software, which powers FLOSS Manuals.
In March 2015 it was announced that Amnesty International was using a pre-release version of Booktype 2.0 to publish its Annual Report on the state of human rights, in multiple languages.
Booktype interface localizations are crowd-sourced from volunteers in a Transifex project.