What makes an application portable? These apps can run from any portable device (a thumb drive, CD, DVD, portable hard drive or other device) without needing to be installed directly on the hard drive of the system you're using. They also don't leave behind any files on the host system, and they don't interfere with other software installed on that system.
For this list, we've compiled some of the best portable open source applications available. Some of these were originally designed by the project owner to be portable. Others are open source applications that have been re-packaged for portability by a third party.
Several groups, notably PortableApps.com and winPenPack, have created suites of portable open source applications. Others offer directories with many individual portable apps. Because these collections and directories are so helpful, we put them at the top of our list. Other individual portable applications come next, organized by category.
As always, feel free to mention other portable open source applications in the Comments section below.
2) winPenPack While its not as well-known as PortableApps.com, winPenPack also offers dozens of open source apps in portable versions. You can download the apps individually or you can get the Full or the Essential suite. Operating System: Windows.
3) Democrakey If you're worried (or paranoid) about privacy and censorship, Democrakey bundles together open source applications for secure Web browsing, secure e-mail, secure chat, encryption, file shredding and anti-virus. You can download it to your own USB drive from the link above or purchase a USB drive with Democrakey installed from Democrakey.com. Operating System: Windows.
4) Tor Browser Bundle Like Democrakey, the Tor Browser Bundle packages together several apps that you can use from a thumb drive to protect your privacy while surfing. It includes Tor, Vidalia, Polipo, Firefox, and Torbutton. Operating System: Windows.
6) OS X Portable Applications This site includes twenty-two free portable applications, many of which are open-source, that can be used on any Mac. The list includes Adium, Audacity, Gimp and more. Operating System: OS X.
7) Pendriveapps.com Pendriveapps.com has an exceptionally large library of portable applications, many of which are open source. It provides reviews and downloads for software in dozens of different categories. Operating System: Various.
8) PortableLinuxApps.org This site offers more than 150 apps that can be downloaded to a USB drive and used from any Linux system running Ubuntu 10.04 (Lucid Lynx) 32-bit, OpenSUSE 11.3 (GNOME) 32-bit , or Fedora 12 (GNOME) 32-bit. Well-known titles on the site include the VLC media player, TrueCrypt encryption software, Pidgin instant messaging, LibreOffice and many others. Operating System: Linux.
12) X-Chromium If you prefer Google's browser, this app is based on the same open source project that is the basis for Chrome. It also allows you to carry your bookmarks and personalization preferences with you. Operating System: Windows.
13) Qt Web Browser Based on Nokia's Qt framework and Apple's WebKit rendering engine, this browser was designed to be lightweight, secure and portable. It's just 6MB, and it offers a highly customizable interface and a long list of privacy-protection features. Operating System: Linux, OS X.