How it works
Every draw here starts with quantum random numbers. Here is where they come from and how they become cards.
Quantum randomness
An ordinary computer generator calculates its numbers from a starting value: they only look random. A quantum generator measures a physical process whose outcome, according to quantum physics, cannot be predicted even in principle.
That does not make the cards wiser. It does mean that no one, not even us, could have known the draw in advance.
Where the numbers come from
The numbers come from the LfD QRNG, a quantum random number generator at Leibniz Universität Hannover that offers its numbers to everyone.
Our server fetches them 1 KB at a time and keeps them in memory. Every byte is used once and then thrown away.
How the cards are shuffled
A byte becomes a card without bias. If the byte falls outside the largest range that divides evenly by the number of cards left, it is discarded and the next one is taken. A simple remainder would make some cards come up more often.
The cards are then dealt one by one from what is left of the deck (a partial Fisher-Yates shuffle). Every card is equally likely in every position.
When the quantum generator does not answer
If the LfD does not answer within a second and a half, the server shuffles with the ordinary Cloudflare generator, and the page says so under the draw. Without a connection to the server, your browser shuffles by the same rules and says that too.
A draw is called quantum only when its numbers really were quantum.
For entertainment
Oracle is made for fun and reflection. The cards do not make decisions for you and do not replace the advice of a doctor, a lawyer or a financial adviser.
Oracle is made by Caféine Software. The site has no ads and no trackers.