Link states

Five states. Destination and short URLs only when `state` is `active`.

• active
• quarantined
• disabled
• blocked
• expired

A link keeps its destination until the owner changes it, unless we restrict it under our Terms (§11). Customers cannot disable a link. Link disable and click analytics are not available. POST /v1/links/{id}/enable turns a disabled link you own back on, unless we restricted it. Creating a link does not set an expiry. Custom domains are not available. A short code is not a secret. Guessing it does not make the destination private. GET /status only says the app process is up.