What app did this person use? Please help!!

[CuriousKitty]

I want to make something like this for my anniversary but can't seem to find the app she used to add the heart.. I've seen something similar before and am wondering if any of you know what app it is! Also, if you know of any free photo grid apps that allow you to have 16 pictures like this please let me know. I have picstitch and you have to pay to upgrade and unlock it.

 

[Darkstar2007]

That looks like Moldiv. If not, I know Moldiv will do the same thing as this app.

 

[sportsman]

Pip camera !