This app is for ambitious and professional photographers who carefully frame their photos in the camera, edits them on computer, and want to post them on instagram as is. Instagram forces you to crop the images to a maximum of 4/5 ratio, but dslr takes 2/3 and phones 3/4. Sometimes the image looks ok cropped, but sometimes it completely destroys it, and a simple app like 2/3 comes to rescue.
How to use:
1. Edit your final image on computer and save it to iCloud Drive or Photos app
2. Open 2/3 and chose the image. Files app has also a share menu called "Copy to 2/3"
3. In 2/3 app customise the frame and logo and tap Share and chose Copy to instagram
4. In instagram resize the photo to fit, otherwise it will be cropped to square