A coalition of human rights and technology groups has launched a tool that lets users check whether their computer has been infected with surveillance software.
Amnesty International, the Electronic Frontier Foundation, Privacy International, and Digitale Gesellschaft have worked together to create the Detekt software, released on November 20.
Amnesty said the spyware spotter is designed for rights activists and journalists but will be freely available to anybody who fears their computer is being used to monitor them.
The tool can be downloaded from the website resistsurveillance.org.
Amnesty said the program was needed as standard antivirus programs often missed spying software.
It said many governments used sophisticated spying tools that could grab images from webcams or listen via microphones to monitor people.
Detekt can currently find eight different pieces of spy software.