Developed by The Document Foundation, the LibreOffice suite is a fork of OpenOffice, meaning the underlying source code is the same, but the software has gone in a different development direction. (LibreOffice was created in 2010 by OpenOffice developers worried about what Oracle, which had acquired Sun Microsystems, the original developers of OpenOffice.org, would do with the code base.)
http://www.libreoffice.org/download