Proof of existence for documents
Proof of existence is evidence that a specific document or file existed at a specific moment. BlockchainSign creates that proof by recording a SHA-256 fingerprint of your file on the Ethereum blockchain — a permanent, public, tamper-proof record that your document existed before that timestamp.
Permanent record
Once recorded on Ethereum, the proof can never be changed or deleted by anyone.
Independently verifiable
Anyone can confirm the proof on Etherscan — no account and no trust in us required.
Content stays private
Only the hash is published. The original file never leaves your browser.
What is a blockchain proof of existence?
Instead of trusting a server's clock or a single company's records, a blockchain proof of existence anchors your file's fingerprint to a decentralized ledger. Because the blockchain is immutable, the record is durable evidence that the exact content existed at — or before — the recorded time.
Proof of existence is not proof of authorship
This is the distinction that matters most, and the one most often blurred. A blockchain record proves that a specific file existed by a specific time and has not changed since. It does not prove who created it — if someone timestamps a copy of your work, the record honestly shows they had that copy, and nothing more.
That is not a weakness so much as a boundary. Because timestamping is cheap, you can do it on every draft, and a dated chain of drafts evolving into a finished work is evidence only the real author can produce. See proof of existence vs proof of authorship for how the two fit together, and what each is worth as evidence.
When you need proof of existence
- Establishing a date for intellectual property, designs or inventions.
- Supporting a claim of authorship with objective, dated evidence of priority.
- Showing a contract or agreement existed before a dispute.
- Demonstrating a file was unchanged since it was recorded.
How to create proof of existence
- Submit your file or text — hashed locally with SHA-256 in your browser.
- We record the hash on Ethereum — creating the permanent proof.
- You receive a lifetime certificate — verifiable forever on the blockchain.
Read the detailed verification steps on the how it works page.