All downloads are at sourceforge. First read the information below.

Browser and Tools

Multivalent.jar (at sourceforge)
The browser and all the document tools are bundled in -- and directly executable from -- a single file.
It's written in Java, so it runs on Solaris, Macintosh OS X (Jaguar or later), Linux, and even Windows. It requires Java 2 v1.4 from Sun, or on Macintosh use Software Update.

Installation is done by simply downloading that single file onto your hard disk. There is no separate installation process; that file is executed directly. Any extension is installed by simply downloading the extension file into the same directory as the browser.

Tools all work well, have been extensively tested, and in many cases outperform commercial alternatives costing hundreds of dollars each. For running instructions, see Tools.

The browser, on the other hand, is a "developer release", meaning that developers can usefully use many parts of the system, but it is incomplete for end users. For running instructions, see Browser.

Optional Packages

If you have a TEXMF tree installed, you can use DVI.jar and use those fonts. If you don't have any TeX fonts, DVIf.jar bundles the BaKoMa version of the Computer Modern fonts, so you'll be able to read many (but not all) DVIs. You only need one or the other JAR, and whatever the case do not put both DVI JARs in the same directory.
JPEG 2000, TIFF, PNM, BMP and WBMP image formats
Add support for these formats by installing the Java Advanced Imaging API Image I/O Tools. Apple has a JAI update available.
PDF relies on a set of "14 core fonts", and looks better if it doesn't have to substitute other fonts. Macintosh OS X has all 14 core fonts, Windows has all but the Zapf Dingbats font, and UNIX may or may not have these fonts depending on the flavor of UNIX or the Linux distribution. You can take advantage the same fonts used by Ghostscript that were developed by (URW)++ Design and Development. Install them in the OS, or alternatively copy them into $JRE/lib/fonts.

Javadoc documentation for the core classes and supporting library.

Source Code
The browser is open source. The document tools are a free bonus and not open source. The browser and tools use a supporting library (packages com.tap and *.Postscript) that is not open source.

The system is explicitly designed to be deeply extended without changing the source code of the core system. It is like Java itself in that to develop in Java you do not need to inspect the source code. All you need are the API and the browser JAR in your CLASSPATH.

However, the easiest way to learn the system is to examine how other extensions are implemented, and since the base system consists of a small core and many behavior extensions (in fact, all user-level functionality is implemented with behaviors), the is an excellent source of examples.

Third-Party Software

See Links.