Below you will find various software which can be downloaded from the Internet
Open Office- a free Office package which containes almost everything a Microsoft Office package has: http://www.openoffice.org/
Libre Office - https://www.libreoffice.org/
Firefox- http://www.mozilla.com/en-US/firefox
Google Chrome - http://www.google.com/chrome
Opera- http://www.opera.com/
Safari- http://www.apple.com/safari/
Vivaldi - https://vivaldi.com/
Thunderbird- a mail client similar to Outlook: http://www.mozilla.com/en-US/thunderbird/
ProjectLibre - ProjectLibre is an open source replacement of Microsoft Project! Download here: http://www.projectlibre.org/
Gimp- an image manipulation program that has many of Photoshops features: http://www.gimp.org/
Irfanview- a small but powerful program which views pictures and even videos: http://irfanview.com/
PrimoPDF - Create PDF files with the "world's most popular free PDF creator". With just one click, turn virtually any kind of file into a 100% industry-standard PDF: http://www.primopdf.com/
PDF-creator- a small program that makes PDF files: http://sourceforge.net/projects/pdfcreator/
VLC media player- a player that plays almost all audio and video files: http://www.videolan.org/
FreeMind- a software which creates mind maps similar to MindManager: http://freemind.sourceforge.net/
XMind- another software which creates mind maps. The basic version is for free but you have to pay for the pro version: http://www.xmind.net
Zotero- for those who are not ready to spend money on EndNote: http://www.zotero.org
R- This is a statistic software similar to SPSS: http://www.r-project.org/
PSPP- another statistic software similar to SPSS: http://www.gnu.org/software/pspp/
Sage- A mathematics software similar to Matlab, agma, Maple and Mathemetica: http://www.sagemath.org/
Open XML / ODF Translator Add-ins for Office - Provides translator to allow for interoperability between applications based on ODF (OpenDocument) standards (currently ODF 1.1) and Microsoft OpenXML based Office applications.
http://odf-converter.sourceforge.net/download.html
PuTTY: A Free Telnet/SSH Client - PuTTY is a free implementation of Telnet and SSH for Windows and Unix platforms, along with an xterm terminal emulator.
http://www.chiark.greenend.org.uk/~sgtatham/putty/
FileZilla - FileZilla is free, open source, cross-platform FTP software, consisting of FileZilla Client and FileZilla Server. Binaries are available for Windows, Linux, and Mac OS X. It supports FTP, SFTP, and FTPS (FTP over SSL/TLS).
http://filezilla-project.org/
MiKTeX - MiKTeX (pronounced mick-tech) is an up-to-date implementation of TeX and related programs for Windows (all current variants).
http://miktex.org/