Sigil Portable is an ePub ebook editor with support for both WYSIWYG word processor style and direct code editing. It's packaged in PortableApps.com Format so it can easily integrate with the PortableApps.com Platform. And it's open source and completely free.

Sigil is a multi-platform EPUB ebook editor with the following features.
Sigil provides advanced automatic conversion features for all imported documents to the Unicode text encoding.
Sigil also offers a metadata editor with extended support for all types of metadata entries (over 200) that enable you to insert a full description for each.

Features
* Online Sigil User's Guide, and Wiki documentation
* Full UTF-16 support
* Full EPUB 2 spec 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 with full support for all possible metadata entries (more than 200) with full descriptions for each
* 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 FlightCrew EPUB validator
* Embedded HTML Tidy: all imported files have their formatting corrected, and your editing can be optionally cleaned

Sigil Portable is packaged in a PortableApps.com Installer so it will automatically detect an existing PortableApps.com installation when your drive is plugged in. It supports upgrades by installing right over an existing copy, preserving all settings. And it's in PortableApps.com Format, so it automatically works with the PortableApps.com Platform including the Menu and Backup Utility.

Sigil 0.7.2 2013.04.14
- Implement issue 2129: Enhance archive filename encoding handling.
- Implement issue 2128: Warnings for non-ASCII characters in filenames.
- Implement issue 2113: Preview should zoom separately from other views.
- Implement issue 1997: Tool to Add Cover image and file automatically.
- Implement issue 1993: Find & Replace should have a Marked Text option.
- Implement issue 2083: Enhance invalid OPF recovery.
- Implement issue 2082: Improve performance of Book Browser refresh.
- Fix issue 2170: Spellcheck should remember position after changing word.
- Fix issue 2148: Don't delete cover image in "Delete unused media files".
- Fix issue 2147: Doubleclick in Delete Files dialog can cause crash.
- Fix issue 2143: Bulk rename with just a number for filename does not use correct number of 0s.
- Fix issue 2121: Wait cursor shows when dialog is open while saving or opening.
- Fix issue 2107: Heading not accepted due to split at end of file.
- Fix issue 2110: Insert Special Character inserts wrong code for nnbsp.
- Fix issue 2021: Importing UTF-16 encoded files results in empty file.
- Fix issue 2088: Ctrl-click on text files does not work in Code View.
- Fix Issue 2071: Anchor dialog has disabled text field.
- Fix Issue 2077: Rename dialog incorrectly sized.
- Fix issue 2081: Book Browser tooltips are not updated when semantics change or for cover images.
- Fix issue 2080: OPF meta title not updated correctly for Add Semantic.
- Fix issue 2079: UI Language dropdown does not show language names for entries containing _.