Blockchain document signing
Blockchain document signing seals a document to a public, immutable ledger so its existence and integrity can be proven by anyone, forever. BlockchainSign records a SHA-256 fingerprint of your document on the Ethereum blockchain and issues a lifetime certificate — for any document, including PDFs, online and offline.
Any document, incl. PDF
Sign a PDF, image, contract, archive or plain text. Any file type works — bundle several into one archive if needed.
100% online
No software, no plugins. Everything runs in your browser and on the blockchain.
Tamper-proof
The blockchain record cannot be altered, so it permanently proves the document existed unchanged.
Sign documents online with blockchain
There is nothing to install. Upload a file or paste text in your browser and the hash is computed locally — we never see your document. We write that fingerprint to the blockchain and send you a certificate you can verify on Etherscan at any time.
Blockchain signing vs. e-signature
A traditional e-signature shows intent to agree. Blockchain document signing adds something a signature cannot: independent, permanent proof of when the exact document existed and that it has not changed since — anchored to a network no single company controls.