What iPhone app lets you upload your own borders/backgrounds for your photos?

I've seen people post photos on Instagram, with the pictures in various sizes, and different images as the background border. InstaSize allows you to make your photos different sizes, but only has a limited selection of borders. I've been searching through so many different photo editing/photo collage apps and can't find anything that does this.

HI! I normally use the edit app "Aviary". You can choose up to 13 borders. But you can also edit your photo in more ways. Adding stickers, effects, HD, cropping, focus, removing zits or red spots, sharpness, and even whitening your teeth. This app normally is for pictures of yourself (selfies), or pictures of beautiful food or scenery. You can change the color of your photo also.

Other apps include Repix, Rookie, Adobe photoshop, Over, etc.