The people behind Sigil, the multiplatform e-book editor, are making progress toward their goal of adding “ePub3 support without disrupting ePub2 editing.”
They’ve just released Sigil 0.8.900, a major overhaul, on the way to Sigil 0.9.0. The program’s regular version for download is now 0.8.7. Already, there’s a plug-in to get ePub 3 from ePub files created by Sigil, even if it can be cumbersome to use compared to a future Sigil designed from the start for optional ePub3 creation.
Supported by donations, Sigil is free and open source and runs on Windows and the Mac and also offers limited Linux support.
Related: Previous TeleRead articles on Sigil.
Note: That’s an old screenshot of Sigil, from Wikipedia.