SSL certificate
The certificate that lets a short domain be served over HTTPS, issued after control of the hostname has been verified.
Updated August 14, 2026
An SSL certificate binds a hostname to a public key and is signed by a certificate authority that first verified control of that name. The protocol has been called TLS for years, but the older label stuck to the file. Without a valid one for your exact hostname, a browser will not open the address without a warning, and messengers and mail clients often refuse to fetch a preview at all — which for a short link means the click never happens.
Certificates for branded short domains are normally issued and renewed by the platform rather than by you. Validation is done through DNS, and delegating the _acme-challenge name with a CNAME is what makes every future renewal automatic: the platform can answer the challenge itself, so you never edit DNS for that hostname again.
When a certificate stays unissued, two causes cover most cases. The hostname is proxied by the DNS provider instead of resolving directly, so validation cannot complete. Or the domain carries CAA records that do not list the authority being used, in which case issuance is refused without a visible error.