Is a coin flip really 50/50?
Close to it. Studies filming hundreds of thousands of real tosses found a slight lean — around 51% — toward the side that started face up. A computer coin has no thumb, so here it's an even 50/50 every time.
Long streaks look suspicious but are normal: in 100 fair flips, a run of six or more of the same side happens most of the time. Flip 100 and check the longest streak yourself.
How does the Coin Flip decide heads or tails?
Choose 1, 3, 5, 10, 20, 50 or 100 flips and press Flip. Your browser draws a random 8-character code and the link becomes /coin/ followed by the number of flips, a dash and the code. The word coin, the code and the number of flips are hashed into a seed for a mulberry32 generator, which produces one number between 0 and 1 per flip: below 0.5 is heads, anything else is tails.
The page then counts heads and tails and finds the longest run of the same side; if two runs are equally long, the one that came first is shown. Everything comes from the link, so the same link replays the same flips on any device, and changing the number of flips gives a new sequence even with the same code. Nothing is kept on a server.
Limits: this is a pseudo-random coin, fair for everyday calls but not a cryptographic or certified generator. It doesn't imitate a real coin's physics, such as the slight lean toward the starting side. Flipping again makes a new link, so settle which flip counts before you start.