The answer to this question is same as the answer of how url shortener works. Accordingly, url shorteners work based on web server functions referred as Redirects or URL redirection. The short URL becomes the new URL, which redirect online users and visitors to the old and long site URL.
Eshortlink shortener is a URL shortener which pays long URLs exceeding 100 characters as input. In the output it converts the respective link into manageable one that has a maximum limit of 20 characters.