Open Source Software:

Source: Taken from Wikipedia

Open source software is software whose source code is published and made available to the public, enabling anyone to copy, modify and redistribute the source code without paying royalties or fees.[20] Open source code evolves through community cooperation. These communities are composed of individual programmers as well as very large companies. Examples of open-source software products are:[21]

FAVORITE: XAMPPXAMPP is an easy to install Apache distribution containing Apache Server, MySQL, PHP and Perl. The X represents any one of four OS (Windows, Mac, Linux, or Solaris)

See Also:
Free Software Directory
Web 2.0 app — Whether in face-to-face or online classrooms, research is showing that student engagement is key to student success.  What better way to improve student engagement and community than with some of the rich Internet tools and applications that are available today.  After all, now that we have flattened the world, isn't it about time that we flattened our classrooms?

Programming language

App Development

Operating System

Server

Client software

Others