How Kaspa Notary Works
A traditional notary witnesses an agreement between two parties. Kaspa Notary does the same thing - except the witness is a blockchain that can never lose records, alter them, or be bribed.
Two ways to notarize
Kaspa Notary supports both agreements between two parties and documents signed by a single party.
Two-party agreement
For contracts, NDAs, and agreements where both sides need to sign.
Upload & Sign
Upload a PDF of your agreement. Add your counterparty's email. Type your name to sign and pay a small notary fee in KAS.
Counterparty Signs
Your counterparty receives an invite link. They review the document, connect any Kaspa wallet, and sign. No account or signup needed - just a wallet.
Sealed on the Blockchain
Once both parties sign, a seal transaction is automatically recorded on the Kaspa blockDAG. The document's fingerprint, both wallet addresses, and the timestamp are embedded in the transaction - immutable proof of agreement.
Single-signer document
For timestamping intellectual property, patents, creative works, or any document where you need to prove it existed at a specific moment.
Upload & Sign
Upload your document and type your name to sign. No counterparty needed - leave the counterparty field empty.
Sealed Immediately
Your document's fingerprint and wallet address are recorded on the Kaspa blockchain the moment you sign. Instant, permanent proof that this document existed at this exact time.
What makes this different?
Cannot be backdated
The Kaspa blockchain timestamps every transaction to the second. No one can claim a document was signed earlier or later than it was.
Cannot be altered
The document's cryptographic hash is sealed on-chain. Change even one pixel and the hash won't match - tampering is immediately detectable.
Independently verifiable
Anyone can check the seal transaction on the public Kaspa blockchain. No need to trust us - verify it yourself.
Works with any wallet
KasWare, Kastle, Kasla, or any Kaspa wallet. No special account or software required.
Use cases
Contracts & Agreements
Freelance contracts, rental agreements, partnership deals. Both parties sign and get permanent blockchain proof.
Intellectual Property
Timestamp a patent idea, design concept, or research paper. Prove it existed at a specific date - before anyone else claims it.
NDAs & Confidentiality
Both parties sign an NDA with private visibility. Only the signers can see the document - the public only sees the proof exists.
Certificates & Credentials
Issue a verifiable certificate. Anyone can check the proof page to confirm it's real and when it was issued.
Creative Works
Timestamp music, writing, art, or code. Single-signer mode seals it instantly - proof of creation date forever.
What is "Hash a File"?
The Hash a File tool lets you compute the SHA-256 fingerprint of any PDF - entirely in your browser. Nothing is uploaded to our servers.
This is how verification works: every file has a unique fingerprint. When a document is notarized, its fingerprint is permanently sealed on the blockchain. Later, anyone can re-hash their copy of the file and compare. If the fingerprints match, the document is exactly what was originally signed. If they don't match, it's been tampered with.
You can also use the Verify tool on any proof page - drop a file and it'll instantly tell you if it matches the sealed record.
Frequently asked questions
Where is my document stored?
Your document is stored on our secure server. Only the original signers can access it. What goes on the blockchain is the document's fingerprint (SHA-256 hash), not the document itself.
What does "upload to blockDAG" mean?
This is an optional feature for small documents (under 2 MB). If selected, the actual file is uploaded directly to the Kaspa network - making it permanently available on-chain, independent of our server. If not selected, the file lives on our server and verification works by re-hashing your local copy against the on-chain fingerprint.
What if I lose my copy of the document?
If your document is stored on our server, you can always download it from your dashboard. If you chose "upload to blockDAG," the document is also permanently on-chain. Either way, the blockchain proof - the fingerprint, wallets, and timestamp - can never be lost.
How do I verify a document is authentic?
Visit the document's proof page and use the "Verify" drop zone. Drop your copy of the PDF - the tool computes its fingerprint in your browser and compares it to the on-chain record. A match means the document is identical to what was originally signed.
Can anyone see my document?
Only if you choose to make it public. By default, documents are private - only the original signers can view the PDF. The public archive shows the proof of existence (hash, wallets, timestamp) but not the document content unless you explicitly allow it.
What Kaspa wallet do I need?
Any Kaspa wallet works - KasWare, Kastle, Kasla, or mobile wallets. You just need to connect it to sign. The counterparty can use a completely different wallet.
How much does it cost?
The notary fee is a small fixed amount in KAS that covers the blockchain seal transaction. The exact amount is shown before you confirm.
Is this legally binding?
Kaspa Notary provides cryptographic proof of agreement at a specific point in time. While blockchain-sealed documents are increasingly recognized in legal proceedings, we recommend consulting a legal professional for matters requiring formal legal standing in your jurisdiction.
Built by Kaspero Labs LLC.
Kaspa Notary
Seal agreements on the Kaspa blockchain.
Immutable proof that cannot be backdated.
Connect a wallet to create and manage your own documents.
Notarized Documents
Public record of documents sealed on the Kaspa blockchain.
No notarized documents yet
Check File Hash
Drop any PDF to see its SHA-256 fingerprint. This hash is unique to the file - change a single byte and it changes completely. No data leaves your browser.
Drag & drop or browse files
PDF - up to 10 MB
What is this for?
A cryptographic hash is a digital fingerprint. When a document is notarized on Kaspa Notary, its hash is permanently sealed on the blockchain. Later, anyone can re-hash the file and compare - if it matches, the document is exactly what was originally signed. If it doesn't, it's been tampered with.
My Documents
No documents yet
Create your first notarized document.
New Document
Drag & drop or browse files
PDF - up to 10 MB
Embedding runs after the seal and takes ~- seconds.
For your confirmation receipt when the document is sealed.
They'll receive a link to review and sign. Any Kaspa wallet works.
Review & Sign
Cost
Covers the blockchain seal transaction.
Pay Notary Fee
Pay to seal your signed document on the blockchain.
Your document has been signed and permanently recorded.
Signatures
This document is a draft
Review the details above, then pay the notary fee to sign and proceed.
Edit Draft
Sign this Document
Review the document above, then confirm and sign below.
Blockchain Proof
Document
Open PDFVerify Document
Drop the original file here to check if its hash matches the sealed record.
Drop PDF to verify
You've been invited to sign
Signatures
Sign this Document
Connect your Kaspa wallet, review the document above, then confirm and sign.
So we can send you a confirmation with the blockchain proof.