eCanCrusher

eCanCrusher is a simple drag/drop utility to recompress and decompress EPUB folders/directory structures. It converts folder into an .epub file and vice versa. Both Mac and Windows versions are available.
website

Blue Griffon

XHTML and HTML editor.
website

Easy Java Simulations (EjsS)

Easy Java/Javascript Simulations, also known as EjsS (and, formerly, EJS or Ejs), is a free authoring tool written in Java that helps non-programmers create interactive simulations in Java or Javascript, mainly for teaching or learning purposes.  EjsS can export simulations as web pages, ePub, and other formats.
website

EjsS Reader (Google Chrome only)

A Reader/Viewer to organize and store EjsS simulations on your local desktop or laptop computer for easy access.  Requires Google Chrome browser.
website

Java Development Kit

Although you only need the the Java Runtime Environment (JRE) to run EjsS and other Java programs, the Java Development Kit (JDK) is needed to create apps for the iTunes and Google Play stores.  Note that the JDK also installs the latest JRE.
website

7 Zip for Windows

7-Zip is a free open source file archiver with a high compression ratio.
website

Archive Browser for Mac

The Archive Browser is an inexpensive program that lets you browse the contents of archives, as well as extract them.
website

Gitden EPub Reader for Android

A good Android reader that supports ePub 3 and JavaScript simulations.
website

Readium

An ePub 3 reader plugin for Google Chrome.  This plugin reads ePub books stored on a local computer.
website

IDPF ePub 3 Validator

The International Digital Publishing Forum (IDPF) site to provide validation information for EPUB 2 and 3 documents. Validate your ePub documents before you release them!
website