Pick the shape of the draw
The choice is mostly about what the result has to look like to the people watching.
A number or a set of numbers — random number generator for a range you define, lottery numbers for the fifteen games with fixed rules, dice when you need dice notation and modifiers rather than a flat range.
One winner out of a list — name picker when you want the answer, spin the wheel when an audience is watching and the drama is the point.
A yes or no — coin flip.
Everyone sorted into groups — team generator, which deals round-robin so 7 people into 3 groups comes out 3/2/2 rather than dumping the remainder in the last group.
A game that runs over time — bingo caller, 75, 90 or 99 balls, driven from one screen.
Checking someone else’s draw — the draw verifier, which is the one tool here that does not generate anything.
The part that makes this category different
Any site can produce a random number. The harder problem is producing one that a sceptical participant will accept afterwards, and that is a chain running across every tool here rather than a feature of any one of them.
It works like this. Run the draw with a seed — a value you choose, or one the tool picks and shows you. The seed makes the draw reproducible: anyone who has the seed and the same list gets the same result, every time. On its own that is not enough, because an organiser could run draws with different seeds until one came out conveniently and publish only that seed.
So a draw also gets a fingerprint of the list it ran against. Publishing the seed and the fingerprint before the draw commits you to both the participants and the method. Afterwards, anyone can paste the certificate into the verifier, which recomputes the outcome and checks that seed, list and result all agree. Change a name, add a late entry, or swap the winner, and the fingerprint stops matching.
This does not prove the organiser is honest. It proves that this draw, over this list, produced this result — which is the part that was previously impossible for anyone else to check.
When you do not want a seed
Leave the seed empty and the draw uses crypto.getRandomValues() instead: your
operating system’s entropy, not a reproducible sequence. That is the right choice
for anything where reproducibility would be a weakness rather than a feature —
picking a password, splitting a bill, or settling an argument. Nobody needs to
audit which of you does the washing up.
Why a browser draw beats the physical object
A real coin is very slightly biased by how its faces are stamped, and lands the way it started marginally more often than not. A cheap die is worse: moulded pips remove different amounts of material from each face, so the six side is fractionally lighter. Neither bias matters for a board game and neither can be removed by being careful.
A draw computed from the operating system’s entropy pool has no physical asymmetry to inherit. It is not “as good as” a real coin — for fairness, it is better.