Short.cm allows creating short links straight from Slack using you own domain.
Follow the instruction below for shortening:
1. Go to your Short.cm account.
2. Open User Menu.
3. Choose the "Integrations & API" tab.
4. Open the "Slack" tab.
5. Click "Connect."
6. Sign in to your Slack workspace.
7. Select a domain.
8. Slack integration is turned on.
9. Type “/shorten” in any Slack channel/conversation and paste a long link.
10. Send this message and the service will respond with a short URL.
Watch a step-by-step video guide to quickly configure Short.cm and Slack integration.