Verifier
Check a receipt.
Paste a receipt copied from the OrderedStrength app and this page answers two questions. Was Jerry's prediction changed after he sealed it? And is its seal in our public record? The record proves the day it was made. No account, no sign-in, and nothing you paste is stored.
In the app, the button that copies a receipt is called Copy the proof. It is on the Accuracy tab of the My Track Record screen, which sits in the app's detailed analysis section, Full Intelligence, under Patterns. Tapping Track Record on the app's main screen also takes you there. The button appears once Jerry has checked his first locked-in prediction against your result. Once Pro is on sale, that screen is part of Pro after your first 28 days, and the same button then sits free right under Track Record on the main screen. If you are not there yet, use the sample receipt below and you will see exactly what the answer looks like.
What this proves, and what it does not
Was it changed afterwards? Before your set, the app turns Jerry's prediction into a long code called a seal. The seal comes from every detail of the prediction, like a seal on an envelope. This page works out the seal again from your receipt. If the two seals match, nothing in the prediction changed. If even one detail changed, they cannot match.
Was it made before the result? Every night, we join all of that day's seals into one code and post it on GitHub, a public website that shows every change. It works like a postmark. If your seal is part of a posted day, your prediction existed before that day ended. To check this, the page asks our server how your seal fits into that day's code. Then your own device does the same math and compares the answer with our copy of the posted list. Our server cannot fake this for a seal it never had.
It proves the day, not the hour. A day ends at midnight UTC, which is 8 pm in New York (7 pm in winter) and 9 pm in Buenos Aires, and we post it a few hours later. Your prediction and your set usually happen on the same day. So this proves that nobody made up the prediction after the result and added it to a day already posted. It cannot show if the prediction was sealed before or after your set. If your seal was posted on a later day than your set (for example, because it was sent again), this check cannot show it was made before the result. We tell you this so you do not have to find it out yourself. The days posted so far are on the record.
For the technically minded: the seal is a SHA-256 fingerprint of the prediction together with a random number, the nonce, which stays on your phone until you copy a receipt or choose to publish your graded predictions, so nobody can guess a seal in advance. Each day's seals are combined in a Merkle tree, and the code posted for the day is its root hash. The full construction is on the specification page.