Rebrandly accepts many of the Unicode (UTF-8) characters and symbols. If a character is not accepted you will be immediately notified with a message on the dashboard.
Not all websites and apps can handle web addresses (URLs) with special characters (anything besides A-Z letters). These characters might cause the link to break or be shortened in a way that makes it unusable. This can happen in text messages (SMS) and some social media platforms like X.
You can find the list of all accepted characters here.