Alarm Computer Technology, also commonly known as ACT, is a privately-held regional electronic security company headquartered in Swansea, Massachusetts. The company was founded by President and primary owner Helder Lemos in 1983.

Alarm Computer Technology offers various products and services, such as burglar alarm systems, fire alarms, CCTV systems, access control and home theater & audio systems. They currently service several thousand commercial and residential customers throughout New England, as well as in New York, New Jersey, and Pennsylvania.

The company is notable for providing a variety of security services to the Dunkin' Donuts restaurant chain, currently servicing over 1,300 Dunkin' Donuts locations throughout the Northeast United States.