Private company

U3

Logo: Kikkerivers, Public domain, via Wikimedia Commons³

Windows-launching software

U3 was a joint venture between Sandisk and M-Systems, producing a proprietary method of launching Windows software from special USB flash drives. Flash drives adhering to the U3 specification are termed "U3 smart drives". U3 smart drives come preinstalled with the U3 Launchpad.² It ceased to exist in 2009.¹ Wikipedia text CC BY-SA 4.0

Last updated Oct 21, 2026.

Overview

2004Founded¹

Industrycomputer industry¹
HeadquartersRedwood City¹
Websiteu3.sandisk.com

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Products and brands

U3 disk mounting: Hardware emulation

A U3 flash drive presents itself to the host system as a USB hub with a CD drive and standard USB mass storage device attached.

This configuration causes Windows disk management to show two drives:

A read-only ISO 9660 volume on an emulated CD-ROM drive with an autorun configuration to execute the U3 LaunchPad, and;

A standard flash drive (FAT formatted) that includes a hidden "SYSTEM" folder with installed applications.

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U3 compliant applications can be (optionally) preloaded by manufacturers.

U3 Launchpad

The U3 Launchpad (LaunchU3.exe) is a Windows program manager that is preinstalled on every U3 smart drive.

The U3 Launchpad automatically starts at insertion of a U3 enabled device.

U3 applications

To be fully U3 compliant, an application has to be programmed to clean up its own data from the local machine. It must also be packaged in U3's special program format. U3 applications will only run from a U3 device. U3 programs can be downloaded from the U3 website and other places. Applications include Opera and Skype and do not need to be installed on the computer.

APIs

The U3 application programming interfaces (APIs) allow U3 programs lower-level access to USB flash drive, and to query the drive letter. The U3 APIs primarily allow developers who choose to use more of the power of U3 to control how their application handles things like device removal and saves data back to the drive such as configuration or documents.

Compatibility

The latest version of U3 launchpad supports Windows 2000 with Service Pack 4, Windows XP, Windows Vista, Windows 7 and Windows 8.

Data can be accessed using any OS capable of reading from USB mass storage devices, unless the U3 device is password-protected.

Issues with older versions

Early versions of the U3 launchpad software had Vista compatibility issues (specifically the Sandisk Cruzer Titanium series with device numbers 2.17, 2.18, 2.19 and 2.20), although this problem could be eliminated by updating the launcher software.

Prior to Sandisk's updated launcher software being released, Microsoft supported U3 by releasing an update to Vista.

From Wikipedia’s article on U3 (software), shared under CC BY-SA 4.0.⁴

Controversies and legal

Criticism

Numerous criticisms have been made of the U3 platform. These criticisms are:

Malware-like integration behaviour

Software comes preinstalled on USB disk and, when using stock Windows settings, roots itself in the system similar to malware. U3 removal is possible, but requires complete data backup.

Questioned use

There are already portable versions of many Windows software available, some of which do not require any proprietary solution to work.

Removed user data, but not all of it

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Recent files and programs had it listed.

Freezing with certain CD writing software

There is a possibility of slowing down or freezing Windows XP Pro if certain Windows drivers that are associated with high-volume data transfers to CD writers using certain CD/DVD burning software installed.

Proprietary format/closed platform

The U3 platform is a "closed" platform / proprietary format. Sandisk, the rightsholders for U3, ask for a 5% royalty from USB flash drive manufacturers who wish to implement the platform on their products.

Two drive letters

As a work-around to the lack of Auto-Play for Flash drives on older versions of Windows, the U3 software creates two drive letters (one which presents itself as a CD to allow Windows' auto-play to start the launcher, and another for storing user data). Although this is the only way to implement auto-start functionality on pre-Windows XP systems, it could be considered a kludge, and the extra drive letter created can be an annoyance. However, it is possible to prevent Windows from allocating a drive letter for the "CD drive" via the Windows "Disk Management" tool—as long as the user has the appropriate rights/authority to do so.

Incompatibility with certain embedded systems

Some host systems—such as photo kiosks, consumer electronics, and other embedded computing devices—cannot correctly mount U3 "smart drives." The problem may arise because the emulated CD-ROM is the first drive presented to the host system. As such, the device is detected as a CD-ROM drive or not at all. Although some newer photo kiosks are U3 aware and can overcome this limitation, it still exists on many platforms.