Sigil is a multi-platform WYSIWYG ebook editor. It is designed to edit books in ePub format.
Features
Free and open source software under GPLv3
Multi-platform: runs on Windows, Linux and Mac
Full Unicode support: everything you see in Sigil is in UTF-16
Full EPUB spec support
WYSIWYG editing
Multiple Views: Book View, Code View and Split View
Metadata editor with full support for all possible metadata entries (more than 200) with full descriptions for each
Table Of Contents editor
Multi-level TOC support
Book View fully supports the display of any XHTML document possible under the OPS spec
SVG support
Basic XPGT support
Advanced automatic conversion of all imported documents to Unicode
Currently imports TXT, HTML and EPUB files; more will be added with time
Currently exports EPUB and SGF (Sigil native format); more will be added with time
Embedded HTML Tidy; all imported documents are thoroughly cleaned; changing views cleans the document so no matter how much you screw up your code, it will fix it (usually)
An actually usable user interface
Native C++ application
What’s new in version 2.4.2
New Features
Added new tool: 'Update OPF Manifest Media Types' to set unrecognized media types based on actual file contents
Bug Fixes
ensure CodeView code highlighting colors coincide with dark/light themes on certain Linux DEs
fix sigil-gumbo gumboc to work with Python 3.13+ - ie. work around backwards incompatible changes in ctypes
fix Replacement Chooser table to allow for multiple line row heights in Before and After fields (regression)
prevent too many warnings when no media types provided in OPF by generating the warning collectively
prevent build warnings by using hunspell's std:string interface (not C char * ones)
fix files in third party code that used latin-1 encoding to now use utf-8
fix old use of 'python' in python code header lines to always use 'python3'
removed user scope installs from winget util they work properly with dependencies
restore Find&Replace if it was open when the user tries to exit Sigil and then aborts the exit
Won't work on my 2022 MacBook Pro. 1/8/25. It downloads but won't open; it just stays "bouncing" in my dock, then I have to force quit because it won't do anything and won't close. I tried 8-10 times. Deleted.
Will sigil ever be compatible with the M1 processor?? I've tried multiple times this year (Nov 12, 2021 today) and it never works. Have a 2020 MacBook Air.
Just a note: This hasn't been a WYSIWYG editor in a while. The dev removed that portion of the app and split it off into a separate app called PageEdit (also open source).