How the Wheel Works
Random source
The winner comes from crypto.getRandomValues, the cryptographically secure random number generator built into modern browsers. It draws on unpredictable system entropy, unlike Math.random, which is designed for speed and is not meant for fair selection.
Each draw produces a 32-bit unsigned integer, which is turned into a number between 0 and 1. That number is the only input to the choice. The site does not use the time, the position of the pointer or your clicks.
Weighted selection
Every entry has a weight, one by default. Add up all the weights to get a total, and imagine laying the entries end to end on a ruler of that length, each taking up space equal to its weight.
The random number is scaled to the length of the ruler. Whichever entry covers that point is the winner. Entries with larger weights cover more of the ruler and are picked more often, and with all weights equal each entry has the same chance. This is called inverse-CDF selection.
Why the animation cannot change the result
The winner is chosen before the wheel moves. The animation then calculates how far to rotate so the pointer ends up inside the winning segment, and eases the wheel to a stop there.
This means spin duration, speed, device performance and the moment you click have no effect on the outcome. A longer spin is only a longer show.
Fairness check
The fairness check runs 10,000 simulated draws on your current wheel using the same code as a real spin. For every entry it shows the expected share, the observed share and the difference.
It also reports a chi-square statistic. In plain words, this adds up how far the observed counts are from the expected ones, scaled by size, and compares the total to a cutoff for a 1 percent significance level. If the total is below the cutoff, the results are consistent with a fair draw. If it is above, check the weights. Even a perfect generator fails such a test about one time in a hundred, so run it again before drawing conclusions.
Limitations
The fairness check is a statistical test, not a certification or an audit. It can show that results look consistent with your weights, but it cannot prove that a random generator is flawless.
The generator is only as good as the browser and device it runs on. The site also cannot stop a person from restarting the wheel until they like the answer. For high-stakes draws, such as legally regulated prizes, use an independent, audited process.