The Geprüfte Sicherheit ("Tested Safety") or GS mark is a voluntary certification mark for technical equipment. It indicates that the equipment meets German and, if available, European safety requirements for such devices. The main difference between GS and CE mark is that the compliance with the European safety requirements has been tested and inspected by a state-approved (but independent) body. The mark is based on the German Equipment and Product Safety Act ("Geräte- und Produktsicherheitsgesetz", or "GPSG").

Testing for the mark is available from many different laboratories, such as BG-PruefZert, the TÜV Nemko and IMQ.

Although the GS mark was designed with the German market in mind, it appears on a large proportion of electronic products and machinery sold elsewhere in the world.