Seal a prediction as a cryptographic commitment anchored to a live Robinhood Chain block — a hash nobody could know before that block existed, so it can't be back-dated. Post the sealed link now; reveal the text later and anyone can verify it's exactly what you sealed. No wallet, no signature.
The text and your reveal key never leave this browser until you choose to reveal. The sealed link you share contains only the commitment + block anchor.
The anchor proves your seal is not older than its block — it can't be back-dated. The upper bound (that you called it before the outcome) comes from when you post the sealed link publicly. Reveal proves the text is exactly what you committed. All math is Poseidon over BN254 — reproducible by anyone with the open-source poseidon-lite.