function flic_kr(aPhotoId) { // aPhotoId argument is Flickr photo id
  if (typeof aPhotoId !== 'number') {
    aPhotoId = parseInt(aPhotoId);
  }
  var enc='', alpha='123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ';
  var div = aPhotoId, mod;
  while (aPhotoId >= 58) {
    div = aPhotoId / 58;
    mod = aPhotoId - (58 * Math.floor(div));
    enc = '' + alpha.substr(mod, 1) + enc;
    aPhotoId = Math.floor(div);
  }
  return shortURL = "http://flic.kr/p/" + (div ? '' + alpha.substr(div, 1) + enc : enc);
}

http://www.flickr.com/groups/api/discuss/72157616713786392/

A short photo id is a base58 conversion of the photo id. Base58 is like base62 [0-9a-zA-Z] with some characters removed to make it less confusing when printed. (namely 0, O, I, and l).

So that leaves an alphabet of: 123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ

flic.kr - Generate Flickr shortened URL

url, javascript

JavaScript