Advanced URL Shortener add-on for Google Docs lets you to shorten multiple long URLs in your document by a click. Long URLs are shortened to goog.gl short URLs.

IMPORTANT: 

- The volume of URLs that can be converted is bound within the Google UrlShortner API Quota Limit
- You are likely to "receive rate limit exceeded" error if you convert 100+ URLs in a while
- After your quota is blown out, you may have to wait for several hours to get the URLs converted again

Free Features:
 - Shorten a single link at a time
 - Extract and download hyperlinks contained in the document
 
Premium Features:
 - Bulk processing to shorten multiple links in a click
 - Shorten by retaining link text
 - View analytics report of each short URL
 - Download and extract URLs from the document without shortening