A number of apps that allow users to stalk employees, romantic interests, or children have been discovered on the Google Play Store.
Researchers at the cyber security firm Avast uncovered seven apps that allow people to track a victim's location, collect their contacts, and view their call history and messages.
The apps, which have names like 'Employee Work Spy' and 'Spy Kids Tracker', all require the snoop to have access to the device they want to spy on. After downloading the app from the Google Play Store, the app then prompts the person who installed it to enter an email address to which the spy data is sent.
"These apps are highly unethical and problematic for people's privacy and shouldn't be on the Google Play Store, as they promote criminal behaviour, and can be abused by employers, stalkers or abusive partners to spy on their victims," said Avast security researcher Nikolaos Chrysaidos, who discovered the apps.
"Some of these apps are offered as parental control apps, but their descriptions draw a different picture, telling users the app allows them to 'keep an eye on cheaters'. We classify such apps as stalkerware, and using aplklab.io we can identify such apps quickly, and collaborate with Google to get them removed."
The researchers reported all of the apps to Google but had already been downloaded and installed more than 130,000 times all together.
Google pulled all seven of the apps from its Play Store after being notified, removing the last of them on Wednesday, 17 July.
Any apps that have already been downloaded will remain on the target device and continue to function.
Some of the apps listed can also still be downloaded to Android smartphones and tablets by installing them directly from the app developers' websites, which can be found through a simple Google search.
Many of the apps market themselves as helping improve employee productivity, with one app named 'SMS Tracker' claiming in its description that it will help businesses "save time and save money".
Its description states: "It will teach your employees to use their time at work wisely, to reduce time spent on messengers and arrive to work in time."
Another app called 'Spy Tracker' claims that it is the best app to "spy on your kids". It offers its users the chance to "find out more about your child's life, interests, friends and plans".