Notarize a file in your own browser.
In plain English
- What it does
- Takes a fingerprint of any file and signs it, so that later you can prove the file has not been changed — not by a word, not by a digit.
- Why it helps
- You send a quote, a contract, a price list or a board report. Weeks later someone says that is not the version I got. This settles it with maths instead of memory — and they can check it themselves without taking your word for anything, or ours.
- What you need
- Any file at all. Then the same file again, later, when you want to check it.
- How long
- A second or two. The file never leaves your computer — there is no account, no upload, and nothing to sign up for.
Drop in a report, a contract, an export — anything. Your browser hashes it and signs a receipt with a key it generates on this device. Later, you (or your auditor, or your client) can prove the file has not changed by a single byte. Nothing is uploaded: there is no endpoint here to receive a file, and you can watch the network tab stay empty.
1 · Notarize
Hash the file and sign a receipt. The file never leaves this page.
2 · Check it later
Drop the same file — or a changed one — and compare against its receipt.
Your public key
Hand this to anyone who needs to verify your receipts. It cannot sign anything and it reveals nothing about the files.
generating…
What this proves, and what it does not
- It proves continuity, not identity. Anyone can generate a keypair, including someone pretending to be you. What a signature proves is that the holder of this key signed these files in this order. Binding a key to a person means publishing its fingerprint somewhere public — which is exactly what we do with our own chain head.
- The timestamp is your computer's clock. It is not a trusted time source. It is evidence of ordering, not proof of the hour.
- The private key lives in this browser and nowhere else. We never see it — there is nothing here to send it to. Clear your browser storage and it is gone for good, and old receipts stay verifiable by their public key but you cannot sign new ones in the same chain.
- A receipt proves the bytes, not the truth. It proves a file has not changed since it was signed. Whether the file was right in the first place is a different question, and an honest tool should not pretend otherwise.
This is the same machinery we run on ourselves
Our own scheduled jobs write receipts in this format every night, chained the same way, and we publish the chain head publicly so the record binds us too — including the nights our own audit produced nothing.