USBlocker takes advantage of built-in functionality of Windows*, allowing a user to toggle the write protection state of USB storage devices quickly and easily. It does this by changing the value of a single registry key. Windows checks this value every time a new USB device is connected and either allows or disallows changes to the contents of the drive.

* Requires Windows XP Service Pack 2 or later

  • Lightweight - uses minimal system resources
  • Displays a clear status icon in the system tray so you can see the write-block status at a glance
  • Can run automatically at startup
  • Can be run with switches from the command line
  • "AutoBlock" feature automatically enables the write-block after a specified amount of time
  • Registry polling feature monitors the registry for unexpected changes to the write-block status, and immediately re-activates the block if another application disables it (this can happen as a result of user policy refreshes)
  • "Administrator Mode" enables advanced options (enable/disable status notification bubbles, autoblock and startup settings, and more)
Limitations USBlocker relies on Windows to control the write-block state for each device, and the only action it actually takes is to update the value of a registry key. It is possible that it will not be able to write-protect an attached drive as intended if the Windows installation has been altered. The Windows USB write-blocking functionality should be verified before attempting to use this software.

USBlocker should not be relied upon as the sole write-protection solution in situations where it is critical to maintain the forensic integrity of data (e.g. forensic evidence collections). In this type of situation, a hardware write-blocking solution should be used.

USBlocker is only effective for devices that Windows recognizes as USB removable media (e.g. flash drives, hard drives). It will not work for any other type of device or interface.

Pricing USBlocker is free for private individuals, non-profit organizations, and government or educational institutions.

You can use the trial version indefinitely, but a license is required to remove the nag screen that appears every 2 hours. No personal information is required to get a free license.

Pricing for any for-profit organizations is $65 per computer. There is no volume license discount at this time.

Please use the contact form for licensing inquiries.

Support All updates to USBlocker will be free of charge, however the program is provided “as-is” with no guarantee of future support. A fully-functional trial version of USBlocker is available so that you can test it before purchasing (a nag screen will appear every 2 hours).

All icons used for the USBlocker utility and this web site were either packaged as part of Windows XP, Mozilla FireFox, or part of the excellent "Silk" icon set provided for free by Mark James at