Sigil 1.6.0

Sigil

Sigil is a free, open source, multi-platform ebook editor. It is designed to edit books in ePub format (both ePub 2 and ePub 3). 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.

Sigil key features:

Free and open source software under GPLv3
Multi-platform: runs on Windows, Mac, and Linux (note Linux only receives limited support)
Full UTF-16 support
EPUB 2 spec support with limited EPUB 3 support
Multiple Views: Book View, Code View and Preview View
WYSIWYG editing in Book View
Complete control over directly editing EPUB syntax in Code View
Table of Contents generator with multi-level heading support
Metadata editor
User interface translated into many languages
Spell checking with default and user configurable dictionaries
Full Regular Expression (PCRE) support for Find & Replace
Supports import of EPUB and HTML files, images, and style sheets,
Documents can be validated for EPUB compliance with the integrated
All imported files have their formatting corrected, and your editing can be optionally cleaned
Plugins!

Sigil 1.6.0 new features:

Find and Replace search targets expanded to include tabbed files, CSS files, OPF and NCX files
Saved Searches now save full search Controls (mode, direction, options, and targets)
Preview loading is now completely asynchronous with a loading progress bar and loading placeholder
Merge will now automatically prevent duplicate ids
Merge will automatically add ids are former file boundaries to prevent TOC, Guide, and href losses
A new Xhtml Highlighter speeds up huge single file loading considerably
Redesigned CodeView Spellchecking to bring it back to Sigil-1.3.0 speeds
The External XHTML editor will now always pass along the OPF path and spine position
to simplify interface with PageEdit (use "Open With" if you want the old behaviour)
Added PyQtWebEngine as a newly required python module for Plugins.
ie. Plugins now have access to browser functionality for implementing e-Readers, more complex guis.

Bug Fixes:

Add Qt workaround for restoring Sigil window sizes when FindReplace left open on macOS
Add missing tr() calls to the tooltips in the Special Character selection dialog
Fix bug when all unused selectors are removed as in css stylesheet - adds a comment placeholder
Make empty Nav have a title to help empty epub passing epubcheck
Fix bug where fonts couldn't be previewed when a space was in the path
Redesigned code to make Merging large numbers of files much faster (Thank you Text2002ans)
Fix bug in blank language field in Spellcheck Dialog (Thank you Text2002ans)
Fix use of different indentation of css via PR from BeckyEbook (Thank you)
Fix typos in plugin framework guide (Thank you Doitsu)
Fix hang on launch when opf manifested files exist inside the META_INF (Thank you un_pogaz)
Fix Metadata Editor bugs related to alternate-script (Thank you Carmina16) (#613)
Fix Metadata Editor bugs related to epub2 event dates (Thank you Octet-nl) (#616)