What app creates the stretched side border effect or blurred border effect?

Many times on Facebook or Instagram you see photos which look like they stretched the sides of the photos. These border effects appear blurred or look stretched as if they dragged the sides to make the photo square. This border effect is done to automatically make photos square, and there are many different variations of the blurred or stretched border effect, and different sized photos may even make the borders more noticeable.

The app "BlurBorder" is shown in the screenshot below. This has many variations of effects that are added. Although some stretch the border, others reflect or give other types of unique border effects. The end result is that your photos are automatically made perfectly square each time.