You may POST an array of files to https://u.iii.st/upload, by default you will get a json response.
If you want a response in something else than json you add a flag to specify what format you want, for example https://u.iii.st/upload?output=csv.
Valid response types are: json, csv, text, html and gyazo.
curl -i -F files[]=@yourfile.jpeg https://u.iii.st/upload