Sigil is a free and open source editor for the EPUB format. It is designed for easy, WYSIWYG editing of EPUB files and for converting other formats to EPUB. It also provides features for advanced users, like direct XHTML, CSS and XPGT editing. You can use it to add any of the metadata entries supported by the EPUB specification and create a hierarchical Table of Contents.

The editor works on all three major platforms: Windows, Linux and Mac OS X.

Sigil is a work in progress, and as such is still missing many features. If you have the programming skills, you can directly contribute to its development. Even if you don’t, just using Sigil and reporting any bugs or missing features on the issue tracker will go a long way towards making it a better application for everyone.

Operating systems: Windows, Mac OSX, Linux
Screen libraries: Qt