How the US-quarter option works in the shared tool, and what its domain redirect does—and does not—mean.
cointossus.com currently redirects to cointoss.uk; it does not host a separate US-localized version. This page describes the US-quarter preset in the shared coin-toss tool, not a distinct service.
A US-quarter preset
When location is available and indicates the United States, the tool can select its US-quarter design by default. The preset changes the coin artwork, not the outcome odds; visitors can choose another available coin design.
How a result is selected
The browser code requests one 32-bit value through crypto.getRandomValues() and maps even values to Heads and odd values to Tails. The 32-bit range has the same number of even and odd values. The result is selected before the animation plays; this describes the implementation, not an independent certification of the browser or device.
Try the heads-or-tails tool or read the randomness explanation for the implementation details and limitations.