Comparisons

What else you might use, and how DNSMint differs.

Magic DNS

nip.io/sslip.io answers any hostname that has an address written into it. Nothing is stored and there is no account, and the two are one service now - sslip.io redirects to nip.io.

Let's Encrypt issues certificates for IP addresses now, so a machine reachable from the internet can serve HTTPS with no name at all. They last six days by rule, because an address is transient - and when it changes, the certificate and every URL holding it go with it.
The hostname is registered rather than derived from the address, so repointing it keeps every client that already has the URL working.
An IP certificate validates over http-01 or tls-alpn-01 only. A machine behind NAT, on a private address, or not answering on 443 cannot have one; a DNS-01 credential certifies all three.
Nobody else is on your domain. Neither nip.io nor sslip.io is on the Public Suffix List, so everyone using them shares one cookie scope and one Let's Encrypt limit.

Dynamic DNS

DuckDNS and No-IP keep a subdomain you claimed in a web form pointed at an address that changes.

Hostnames are created and retired over the API, rather than claimed by hand from a fixed allowance.
Each hostname has its own challenge record, so a fleet renews certificates at the same time instead of one at a time.
The domain is yours alone rather than the provider's, shared with everyone else on it.

Buying your own domain

There is nothing to buy or own first, which is the step a program cannot do on its own.
One registrable domain is one certificate limit, one cookie scope and one blocklist fate for everything under it. Here every account has a domain to itself, and tenants can be spread across several.
A key can be scoped to a single hostname. A zone token can rewrite or delete the whole zone.
With a managed certificate, the certificate comes back from the same API as the hostname and we renew it, rather than it being an ACME client, a plugin and a renewal to run yourself.

Tunnels

ngrok and Cloudflare Tunnel give a public URL to a machine with no public address, by carrying every request through their network. With no public address a tunnel is the only option and none of the below applies.

We answer DNS and stop. Your users connect straight to your server, so nobody else's outage, latency or rate limit sits in the path.
TLS terminates on your machine, not at a provider's edge where the plaintext is readable.
The hostname is yours to repoint. Leaving a tunnel means changing every client that has the URL.
Nothing is metered on how much the service is used.

Programmable DNS

DNSimple and deSEC run the nameservers while you drive records over an API. The unit is the zone, and a zone is a domain you bring.

The domain is ours and already delegated, so nothing has to be bought or verified before a hostname exists.
The hostname is the unit, so a fleet spread across several domains is the same work as keeping it on one.
No per-zone record ceiling to design a fleet around.
Every domain is signed and its DS published at the registry before it serves anything, rather than being a setting to remember per zone.