These portable apps can be downloaded from trusted sources like PortableApps.com, which verifies the software it distributes.
In software terms, a portable application is a version configured to run without a traditional installation process. It is designed to be executed directly from a removable storage device, like a USB flash drive, or a local folder. AutoCad 2013 - Portable-
Obtain the portable version (often in a .zip or .rar archive). These portable apps can be downloaded from trusted