What is the app you can get white borders around your photos?

Basically people on instagram (phone app) have white borders around their photos and i was wondering how you get them because i cant find the right app and it is very annoying. By the way i have an iphone so it must be an iphone app on the app store:)

thanks x

Added (1). It definatley isn't on instagram (how to do the borders) they are like a thick border- and you can change the thickness of it

There is a border button on instagram that sometimes makes white borders otherwise the app Photo Grid makes borders and collages

Square ready:) that's what I use and its a really good app