Connect your router

Setting this up on your router is the best option: it keeps updating even when your computer is off. Most routers have a built-in "DynDNS" or "DDNS" section that speaks the standard KeepDNS uses.

You will need three things from the app:

Update URL: https://keep-dns.nl/nic/update
Username: your hostname label (for example "myhome")
Password: your update token

FRITZ!Box

Go to Internet → Permit Access → DynDNS. Choose provider "Custom", set the update URL to https://keep-dns.nl/nic/update?hostname=<domain>&myip=<ipaddr>, and fill in your hostname, username and token.

Synology

In DSM go to Control Panel → External Access → DDNS → Add, choose a Customized provider pointing at keep-dns.nl/nic/update, then enter your hostname, username and token.

ddclient (Linux)

protocol=dyndns2
use=web
server=keep-dns.nl
login=myhome
password=YOUR_TOKEN
myhome.keep-dns.nl

A plain cron job

If you would rather not touch the router, any always-on machine at home can update KeepDNS every few minutes:

*/5 * * * * curl -s "https://keep-dns.nl/nic/update?token=YOUR_TOKEN"