How blockchain notarization works, end to end.
A notaros proof is a chain of three simple, verifiable facts: a fingerprint that only your file can produce, a timestamp only a blockchain can grant, and a certificate anyone can check without us.
Your browser fingerprints the file
When you choose a document, notaros computes its SHA-256 hash locally, using the browser’s built-in WebCrypto. A hash is a one-way 64-character fingerprint: the same file always produces the same hash, changing one byte changes it entirely, and the original file can never be reconstructed from it. The file bytes never leave your device — only the 32-byte hash is ever transmitted.
notaros anchors the fingerprint on Base
We record the fingerprint in a smart contract on Base, an Ethereum layer-2. The block that includes it carries the network’s own timestamp, which becomes the authoritative proof-of-existence instant. notaros fronts the on-chain cost and gas — you never need a wallet or crypto to use the full service.
And submits it to Bitcoin via OpenTimestamps
In parallel the fingerprint is committed to Bitcoin through the open OpenTimestamps protocol. Bitcoin’s proof-of-work gives the strongest long-term permanence available; OpenTimestamps aggregates many documents into one Bitcoin transaction so the cost stays negligible. Your certificate carries the resulting .ots proof.
You receive a self-contained certificate
The deliverable is a compact JSON proof certificate — {hash, algorithm, chainId, contract, txHash, blockNumber, logIndex, timestamp} plus the optional Bitcoin ots proof — accompanied by a signed PDF certificate for the full service. It is everything a third party needs.
Anyone verifies it — without notaros
To check a proof, a verifier re-hashes the file and reads notarizedAt(hash) on the Base contract with any public RPC, and optionally runs ots verify against Bitcoin. Our free verifier does this in your browser and never contacts us; you can also do every step by hand. If notaros disappeared, your proof would still stand. Read why that independence matters →
0x + 64 hex). There is nothing for us to store, read, or be compelled to disclose.Ready to seal a document?
It takes under a minute, needs no account, and produces a proof you own outright.