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 Godaddy for a subdomain, enable the service for your main domain.
When your main domain is active in Godaddy, add a subdomain.
Godaddy configurations
Sign in to your Goddady account.
In the Domain tab and click Manage DNS:
Click Add New Record:
Fill in the following information:
Type - CNAME
Name (Host) - your subdomain name, for example: go
Value (Points to) - cname.short.io
TTL - 1 Hour
Click on Save to confirm the changes:
Short.io configurations
Sign in to your Short.io account.
Click on Add domain and then on Add own domain:
Enter your domain name and click on This is domain I already use for website or blog:
Select an option according to your subdomain name and click on Add domain.
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.