InstaSize is a free app for iOS that lets you post photos on Instagram without having to crop them. You can also try out custom sticker design packs, use layers, and create collages with frames.
POST ENTIRE PHOTOS ON INSTAGRAM
ADD FILTERS, OVERLAYS AND TEXT TO YOUR PICTURES
CREATE FRAMES & COLLAGES
EDIT & CROP
CUSTOM INSTAGRAM HASHTAG
SHARE TO INSTAGRAM AND OTHERS
Additional resources for InstaSize for iOS