Write your books and courses using Markdown, GitBook will convert it to a complete static website.
Installable using npm. A companion app (pictured below) to create your books – in case you want a live preview along your edits – is also available.
Building the book to a PDF/eBook is also possible … strongly considering to rewrite my course materials, already freely available online.
GitBook: Build beautiful interactive books using GitHub/Git and Markdown →
Example Book: Learn Markdown →