Today I learned about sslip.io, a handy DNS service that maps special domain names directly to IP addresses, eliminating the need for manual DNS setup or editing your hosts file.

I noticed it when experimenting with Coolify and needed to test the local service at app.localhost.

For example, the URL 192-168-1-100.sslip.io automatically resolves to 192.168.1.100. It works well for both IPv4 and IPv6 addresses and is especially convenient when testing local services that need domain names—like obtaining valid SSL certificates from Let's Encrypt.

Here's what makes sslip.io especially useful:

  • No more manual /etc/hosts modifications.
  • Instant support for HTTPS and valid SSL certificates.
  • Easy setup for local development, demos, and staging environments.

It also works with custom subdomains, such as app.192-168-1-100.sslip.io, which also resolves neatly to your IP.