It is not necessary to register a new domain name for shortening links if you own one that works properly. Create a subdomain using a domain you already have.
Note: Before using Hostgator for a subdomain, enable the service for your main domain.
When your main domain is active in Hostgator, add a subdomain.
Hostgator configurations
Sign in to your Hostgator account.
In the Dashboard, click on Domains:
Navigate to the Advanced Tools panel and click on Manage next to Advanced DNS Records:
In the Mange Advanced DNS Records screen click on Add Record:
In the records settings provide the following information:
Type: CNAME
Refers to: Other Host
<your-subdomain-name>, for example: mysubdomain
Alias to: cname.short.io
TTL: select a period based on your preferences
Click on Add.
The DNS record is added to your domain settings:
Short.io configurations:
Sign in to your Short.io account.
Open the User menu and click on Add domain:
In the next screen click on Add my own domain:
Enter your domain name, select This is domain I already use for website or blog.
Select an option according to your subdomain name and click on Add domain, for example:
Open the Domain settings and check if the domain is in status Active:
Important note: If the domain is Inactive then wait for a few hours and click on Refresh to check if the status has changed.
You will receive an email from the Short.io team informing you that the domain is now configured. Feel free to shorten your links and enjoy Short.io.