Learnt from a friend yesterday that there are spy apps out there which someone with access to one's phone can once install to monitor calls and and even chats.

How true is this? And how can one check for existence of such on their phone?

Yeah, but you'll know!. I used to remotely install Spy apps on People's device for fun during Android jelly bean, Kitkat and lollipop. I stopped at Marshmallow because it got a bit advanced and noticeable. Do yeah it does work but you'll know you are been spied on.

falcon01:
Yeah, but you'll know!. I used to remotely install Spy apps on People's device for fun during Android jelly bean, Kitkat and lollipop. I stopped at Marshmallow because it got a bit advanced and noticeable. Do yeah it does work but you'll know you are been spied on.

Are you for real? Remotely? How is that possible and how will one know if they are being spied on?