SumatraPDF is a multi-format (PDF, EPUB, MOBI, FB2, CHM, XPS, DjVu) reader
for Windows under GPLv3 license, with some code under BSD license.

The main source repository is at http://code.google.com/p/sumatrapdf/

A read-only git mirror is at https://github.com/kjk/sumatrapdf

Want to join the project and contribute code? Read
https://code.google.com/p/sumatrapdf/wiki/JoinTheProject

To compile you need Visual Studio 2008, 2010 or 2012. Open the right solution
from vs directory.