Free app that screenshots snapchat without letting the person know in the play store?
What about a screen video recorded?
most of these apps are removed from the playstore if they are named/described as apps that save snapchat images/videos but there are loads of screen recorders like AZ Screen Recorder a quick search will turn up more then there is casper an app that you have to install its quite easy just look at some youtube vids if you dont know how to install downloaded apks casper(dot)io/