A computer cable tester is a device that is used to check that cables are functioning correctly and in a safe manner. Like all things, computer cables deteriorate with normal wear and use. Wire near connectors is especially prone to damage. Cables may also become damaged due to electrical spikes caused by lightning and other sources. From time to time, cable manufacturers may also inadvertently sell a defective computer cable. A malfunctioning computer cable may not work as intended, cause damage to devices to which it is connected and poses a real safety hazard.

All computer cables have an intended function or connection. A computer cable tester can check a cable to ensure that is properly connected and performing its intended function. Broken computer cables may have unintended connections. These are also known as short circuits. A computer cable tester can detect the presence of unintended signal in a computer cable and alert owners to potential dangers. A computer cable that is short circuiting may damage devices and presents a real danger in terms of possible fire and electrocution. Cables found to be short circuiting should be disposed of immediately.

There are three general categories of computer cable testers:

Verification: These types of testers are the most simple and perform checks for intended circuits and short circuits with ease.

Qualification: Testers of the qualification variety can perform checks for intended circuits and short circuits like verification testers. Additionally, they are able to provide users with the type and quality of data a cable is able to transmit.

Certification: These testers are able to perform checks for intended and short circuits and provide information about the type and quality of data a cable may transmit. Furthermore, certification computer cable testers are able to certify that a cable meets engineering specifications. Some certification testers also have the ability to provide a full schematic map of connected circuits.

The best computer cable tester depends on its intended use. For quick troubleshooting of a home computer or home theater system, a verification tester may be all that is required. For more in-depth, or professional networking and computer engineering projects, the more robust capabilities of a qualification or certification tester may be put to good use.