Digital Notary on the Blockchain
A digital notary proves that a document existed at a specific point in time — without a human notary, an appointment, or a fee per page. BlockchainSign is a blockchain notary: we record a unique fingerprint of your file on the Ethereum blockchain, giving you a tamper-proof, permanent record anyone can verify independently.
Why notarize a document on the blockchain?
A traditional notary stamps paper to confirm it is genuine and when it was signed. Blockchain notarization does the same job for digital files — contracts, agreements, designs, source code, photos and more — but the proof lives on a public, decentralized network that no single party controls and no one can alter after the fact.
No trusted authority
You don't rely on a single timestamp authority. The record sits on a distributed blockchain network, free from control and manipulation.
Tamper-proof
Once your fingerprint is on the blockchain, it cannot be changed or deleted by anyone, including us.
Private
Only the SHA-256 hash of your file is recorded. Your file never leaves your browser, so the content stays private.
How blockchain notarization works
- Submit your file or text — the SHA-256 hash is computed locally in your browser.
- We notarize it on Ethereum — the hash is written permanently to the blockchain.
- You receive a lifetime certificate — proof you can verify on Etherscan at any time.
See the full walkthrough on the how it works page.
Digital notary vs. online notary
An online notary still depends on a licensed person and a central provider that could shut down. A blockchain digital notary depends only on the Ethereum blockchain — your certificate stays verifiable even if our service disappears, because the record is public and permanent.