Short.io is a flexible shortening service, as you can choose the sensitivity by yourself. Short.io automatically creates non-case-sensitive links, but if you prefer case-sensitive links more, turn on this function in the "Domain settings" tab.

1. Go to the short URL list.

2. Open the "Domain settings" page.

3. Put a check next to "Make case-sensitive the slugs of the links."

4. Save.