[amluto]

I use example.org. An explicit http://example.org does the trick when needed.

[aaronbrethorst]

Me too. Visiting the aforementioned URL is the only way I can consistently get captive portal login WiFi networks to work on my Mac. Amazing how busted this experience is...

[CarVac]

Firefox always gives me a button that directly opens the portal login page.

[pabs3]

That one supports https too :)