Can someone recommend an app to resize a photo to 1:1 aspect ratio? There are lots of options to crop, but I want to resize so I keep the full photo and add black bars so that the photo is 1:1.
Well, your best bet is 6tag where you can insert black or white bars to fit a whole pic in an Instagram photo.
(Nokia Camera can resize to 1:1 ratio although sadly without the black bars for you.