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See why it works. Then try to break it.

Six quick missions that use the same cryptography as every SealProof document, running right here in your browser. Nothing you type leaves this page.

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Every document gets a fingerprint: a SHA-256 hash, 64 characters worked out from every letter in it. SealProof uses it to tell whether anything changed.
🎯 Change just one letter or number in the contract below.
Jordan Mitchell agrees to pay Avery Ross $5,000 by October 1, 2026.
Original fingerprint
Fingerprint now

Want the formulas? Read the math behind SealProof, or test yourself with the 2-minute quiz.