Expand a shortened URL into the original

expand-url.el

(defvar url-pattern "https\?://[-_.!~*\'()a-zA-Z0-9;\/?:\@&=+\$,%#]+")

(defun expand-url-region (beginning end)
  "Expand shortened URLs within region."
  (interactive "r")
  (save-excursion
    (goto-char beginning)

    (setq expanded-text "")
    (setq cursor beginning)
    (while (re-search-forward url-pattern end t)
      (setq beginning-of-url (match-beginning 0))
      (setq end-of-url (match-end 0))

      (setq expanded-text (concat expanded-text
                                  (buffer-substring cursor beginning-of-url)
                                  (expand-url (match-string 0))))
      (setq cursor end-of-url))

    (setq expanded-text (concat expanded-text (buffer-substring (point) end)))
    (delete-region beginning end)
    (insert expanded-text)))

(defun expand-url (short-url)
  "Expand a shortened URL into original one."
  (let ((url-request-method "HEAD"))
    (with-current-buffer (url-retrieve-synchronously short-url) (url-view-url t))))