EMC testers are devices used to test or monitor parts and products for electromagnetic compatibility (EMC). Electrical and electronic products which meet published EMC standards do not emit levels of electromagnetic (EM) energy that cause electromagnetic interference (EMI) in surrounding equipment. They are also able to withstand electromagnetic energy in the surrounding environment. Typically, EMC testers are used to test, monitor and measure levels of electrostatic discharge (ESD). ESD, the sudden and momentary flow of electric current between two objects at different electrical potentials, is often caused by static electricity. In some cases, ESD damage from tribocharging or electrostatic induction may produce visible or audible sparks. In others, ESD subjects semiconductor materials to high voltages.

There are many different types of EMC testers. Some are battery-operated and hand-held. Others have a base unit, external power supply, and power supply cable. Hand-held EMC testers are lightweight devices with an integral liquid crystal display (LCD). Larger EMC test equipment such as transient test systems are designated to replicate not only ESD, but also electric fast transients (EFT) or burst, combination wave generators (CWG), power frequency and pulse magnetic fields, and both AC and DC dips and interrupts. EFT can cause microprocessors to malfunction or reset, thus disrupting normal operations. EMC testers that functions as combination wave generators can simulate a surge event in power lines. These EMC testers can also be used to simulate lightning strikes or short-circuit fault currents, which can generate high-level, short-duration magnetic fields.

EMC testers comply with published standards from organizations such as the American Society for Testing Materials (ASTM), the European Committee for Electrotechnical Standardization (CENELEC), the International Special Committee for Radio Interference (CISPR), the International Telecommunications Union (ITU), the European Telecommunications Standardization Institute (ETSI), the International Electrotechnical Commission (IEC), and the International Standards Organization (ISO). EMC testers also comply with published standards from SAE International, an organization which serves the aerospace and automotive industries; and from the Canadian Standards Association (CSA), a non-profit association which certifies electrical devices for use in Canada. EMC testers that are designed for the U.S. military should meet application military standards.