Or alternatively http://httpforever.com/

Similar to HTTPS-only being built into web browsers, isn't captive portal detection built into all modern OSes? What's the badly-setup wifi network that requires you to open your browser but doesn't get detected properly by the OS as a captive portal?

it isn't so much "badly" set up as maliciously set up. Captive portal vendors like to find ways of defeating the operating system's captive portal detection, because it hinders their ability to show ads after the captive portal login process.

Many don't because the captive portal works differently than the regular browser, I'm guessing. If you exit the captive portal on iOS (say to look up a password), you can't just go back to it, you have rejoin the network and start over.

It's funny that if I navigate to this site with HTTPS-only mode, it redirects to an HTTPS page.

Beat me to it. beats the hell out portscanning the subnet at the airport

Thanks! I'll stop using captive.apple.com now that I know about this!

You can also use example.com. I find that easier to remember.

The example names are just examples, it so happens that today they have a web site and it isn't HSTS. Tomorrow maybe they have HSTS. The week after maybe they get rid of the web site. The names are merely examples, and so it's probably a bad idea to use them for any other purpose.

Cool, they even generate subdomains dynamically to avoid caching