Frequently asked questions.
What blockchain notarization gives you, what it doesn’t, and how notaros works — in plain terms.
What is blockchain notarization, or proof of existence?
It is cryptographic evidence that a specific document existed at a specific point in time. notaros records a SHA-256 fingerprint of your file on public blockchains; because those records are permanent and independently timestamped, they show the document existed no later than that moment — without relying on anyone’s word for it.
Does notaros see or store my document?
No. Your file is fingerprinted with SHA-256 inside your own browser. Only the 64-character fingerprint is sent — never the document. There is nothing for us to read, store, leak, or be compelled to hand over.
How does someone verify a notarization?
They re-compute the file’s SHA-256 fingerprint and check it against the blockchain record, using a public block explorer and OpenTimestamps — or the offline verifier we give you. Verification never requires notaros to be online or in business.
Which blockchains does notaros use?
Every full-service proof is anchored to Base and to Bitcoin through OpenTimestamps. Bitcoin gives the strongest long-term permanence; Base gives fast, low-cost confirmation. You get both.
Is a blockchain notarization legally valid?
notaros produces strong, independent evidence that a document existed at a point in time and has not changed since. How that evidence is weighed varies by jurisdiction and use, so treat it as robust proof of existence and integrity, and consult a qualified professional for a specific legal matter. notaros is not identity notarization or Remote Online Notarization (RON).
What does it cost?
Three published, self-service prices — no account, no quote from a human. Full service (web) is $25 per document: both anchors, a signed PDF certificate, and hosted plus offline verifiers. Programmatic anchoring through the API, MCP, A2A, or x402 is $3 per anchor — a signed JSON receipt plus an OpenTimestamps .ots proof, no PDF. Anchoring many documents as one Merkle batch drops the per-document price automatically on a published curve, from $3 down to $0.15 each — computed by /quote, no negotiation. Pay-as-you-go in USDC or USDT, no subscription.
Is notaros a notary public or Remote Online Notarization (RON)?
No. notaros provides proof of existence and integrity — evidence that a document existed at a time and has not changed. It does not verify identity, witness signatures, or provide RON. Where the law requires a commissioned notary, use one.
What is the difference between Base and Bitcoin anchoring?
Base (an Ethereum layer-2) gives fast, low-cost confirmation and a smart-contract record you can query directly. Bitcoin, via OpenTimestamps, gives the strongest long-term permanence. Full service uses both.
What if notaros no longer exists — can I still verify my proof?
Yes — permanently, and by design. Your proof does not rest on notaros; it rests on three open standards that outlive any company. First, SHA-256 (NIST FIPS 180-4) is the fingerprinting algorithm built into every operating system and security tool, so anyone can recompute your file’s fingerprint forever. Second, the Merkle construction is the one standardized in RFC 6962 — the Certificate Transparency system that underpins web-PKI — and your proof file names the exact construction, so anyone can reproduce it with open-source verifiers. Third, and most important for the long term, every full-service proof is committed to Bitcoin through OpenTimestamps: a self-contained .ots file plus the Bitcoin blockchain proves your document existed, trusting no company at all. The Base anchor is only a fast, low-cost convenience — the durable guarantee is Bitcoin. Verifying uses standard public tools (sha256sum or openssl, the OpenTimestamps client, and any Bitcoin block explorer) and the self-describing proof file. notaros never has to exist, or be online, for your proof to stand.
Do I need notaros to verify a proof?
No. Verification is entirely client-side and independent. You re-compute your file’s SHA-256 fingerprint with a standard tool, then confirm it against the public record — the Bitcoin timestamp via the open OpenTimestamps client, and the Base anchor via any public block explorer. Our hosted and downloadable verifiers are conveniences, not requirements, and none of them contacts notaros to do its job. If we vanished, every proof we ever issued would still verify against the public blockchains, with tools that are not ours.
Can I notarize any file type?
Yes. Notarization works on the file’s bytes, so any format works — PDFs, images, video, archives, source code, datasets. The content is never inspected or revealed.
Do you keep a copy of my document or its fingerprint?
The document is never uploaded. The fingerprint you anchor is, by nature, published on the public blockchain — that is the proof. notaros keeps no private copy of your file.
What payment methods do you accept?
USDC and USDT only — dollar-denominated stablecoins, on multiple blockchains (Base and other supported EVM networks, Tron, and Solana). notaros does not accept credit or debit cards, bank transfers, PayPal, cash, or any other cryptocurrency or token. Payment is pay-as-you-go, in full, once per notarization: $25 for the full-service web proof, $3 per programmatic anchor, and less per document in bulk — with no account, no stored balance, and no subscription. You pay a one-time address the exact amount, and notaros fronts the on-chain anchoring cost and gas, so you never need to hold a chain’s native gas token.