Windows stores file association information in the Registry. So, it’s not possible to open a file by double-clicking in a portable application that you carry on a flash drive. Sure, you can associate the file extension to a portable app on your own computer, but it’s not recommended to change associations on a public computer.
That’s where you can eXpresso, a free portable software, that can temporarily assign file extensions to any selected applications. Using it you can assign extensions to portable and installed applications.
EXpresso sits in the system tray and becomes active whenever a file is launched that has no association in the software’s database.
You can now browse and associate the extension with a software you want. As long as eXpresso is running in the background, the new file association will stay active and always open it with the software you choose here. You will get many prompts (as above) while the initial configuration takes place. This can be prevented by manually entering file types in the database via the program options.
If at any time you need to bypass eXpresso’s association or launch the selected file extension in an alternative software, you can use the hotkeys Shift – to launch the file in the default program, or Alt – to launch it in a second alternative program, if one is configured.
EXpresso saves relative paths to a software, making it an ideal companion for a flash drive.
EXpresso works with 32-bit and 64-bit versions of Windows XP, Windows Vista and Windows 7.