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 proves your document existed before that timestamp.
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.
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.
When you need proof of existence
- Establishing a date for intellectual property, designs or inventions
- Proving authorship of content, code or creative work
- 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.