A Danish security vendor is offering a free tool designed to inform users when their applications need patching.

Secunia released the beta version of Personal Software Inspector for download, a client program that periodically checks to see if new updates have been issued for some 4,200 applications.

After installation, the tool inventories a computer's software and versions. It classifies programs as "insecure," "end-of-life" or "up-to-date." The tool then runs when the computer is started.

When a patch is issued for a program on a user's computer, the tool displays a pop-up window in the lower right-hand corner of the screen, said Thomas Kristensen, Secunia's chief technology officer. Another panel provides a download link for the patch.

Personal Software Inspector is intended to get users to apply patches soon after release, as hackers increasingly are trying to exploit vulnerabilities in a wider range of applications. Users may also be uninformed about a new patch, Secunia said.

Some software programs, such as Apple's QuickTime and the Firefox browser, will check on startup to see if patches are available and download and install those patches. But Kristensen said not all programs do this, and sometimes those mechanisms don't work properly.

"I'll argue we are more reliable than other update mechanisms," Kristensen said.

Other products, such as VersionTracker, will notify users when a new software version is available. But Kristensen said Secunia's software and service is focused on security, rather than merely alerting users when any new software version is released.

Secunia monitors the Web sites of a large number of software vendors for security advisories. Those advisories are put into a database, and the Personal Software Inspector polls the database periodically to check for changes, Kristensen said.

Secunia is licensing Personal Software Inspector to other vendors for use in security software suites. Two deals have been made so far, but Kristensen said he could not yet reveal the companies.