A decoy app is installed on an electronic device with the purpose of hiding whatever is inside, such as pictures, messages, or videos. The app itself will have a seemingly normal icon (e.g. a calculator, sporting app, or utilities app). These apps hide in plain sight and always appear like something that someone snooping would not think to click on.

Decoy apps look and often provide the same function as the App they represent. On a decoy calculator, the calculator will work but will also provide an additional function – access to a hidden compartment controlled by a passcode. They will prompt the user to enter a passcode, re-enter the passcode to confirm, and then add any content that they want to hide from others.

The sole purpose of decoy apps is to throw off curious parents, teachers, or friends by making the app appear innocent and difficult to identify as something suspicious.

Previously, apps that hid content were known as vault, safe, or secret apps and were identifiable because the app’s artwork looked like a safe or a vault. Many people legitimately use these types of apps to store passwords and details linked to credit cards and bank accounts. Decoy apps are trickier to identify by their artwork as they can look like a calculator and function as a calculator, but also have a hidden compartment.

The only way to access the content hidden behind the decoy app is to enter the correct passcode. Where decoy apps appear as a piano, for example, you must enter a sequence on the piano to access the hidden content.

Many decoy apps are removed from the app stores, which means that you can no longer download the app yourself. However, once an individual has the app installed on their phone, they still have access to and use of it, even if it is removed from the store.