Thursday, October 22, 2026
Updated Oct 23
The Brier Index
Ledger

Proof the forecasts came first

Anyone can say they called it. This page lets you check that a forecast existed before the price it is graded on.

Every day, when the forecasts are made, we take a fingerprint of them and send it to OpenTimestamps, a free public service that writes it into the Bitcoin blockchain within a few hours. After that, nobody can change a forecast or claim it was made earlier, including us: the fingerprint would stop matching.

Forecasts ofFingerprint (SHA-256)StampedBitcoin blockMade before
Oct 22
forecasts · proof		 48bee8b0 cd3e22e4 e04a0bc1 7b349384 cbb5d775 70cb3f4d f010017c d7fd2812 Oct 23 972,695 2 of 3 dates

"Pending" means the fingerprint is with the OpenTimestamps servers and waiting for the next Bitcoin block, which usually takes a few hours. "Made before" counts how many of that day's three forecasts (1, 7 and 30 days) were stamped before the close they are graded on. The ledger starts with the forecasts of Oct 22, 2026; the first day was stamped after its 1-day close, and it says so above. Earlier forecasts are on the site but were not stamped.

Check it yourself

  1. Download a day's forecasts and proof files from the table.
  2. Open opentimestamps.org and drop both files on the page. It tells you the Bitcoin block and the time the fingerprint was recorded.
  3. Or, on a computer with the OpenTimestamps client: ots verify 2026-10-22.json.ots
  4. The fingerprint in the table is the SHA-256 of the forecasts file (shasum -a 256 2026-10-22.json), in groups of eight characters for readability.

The forecasts file holds exactly what the index published that day: the starting price, the percentiles and the chances, for each horizon. Prices are the Binance BTC/USDT close at 00:00 UTC.