Create a fingerprint
Use the local hasher or your own application to calculate the file's SHA-256 hash on your device.
Public proof. Private file.
Permanent proof of existence.At just $1.
Create verifiable proof of existence, ownership, and integrity.
Protect source code, algorithms, designs, documents, ideas & know-how, innovations, proprietary knowledge, trade secrets, confidential processes, business plans, pitch decks and strategies.
Your file stays privateOnly its fingerprint is sent
Exact file matchingSHA-256 fingerprint
Arc smart contractRecorded under your wallet
Anyone can verifyNo account needed
01 / Check a proof
Verify a BlockchainProof
Select the original file or paste its SHA-256 fingerprint.
Result
Paste a file fingerprint to check the smart contract for matching proofs.
02 / How it works
How it works
Pay 1 USDC
Connect your wallet and approve one transaction on Arc for 1 USDC, plus a network fee of under 1 cent, also paid in USDC.
Record the fingerprint
The BlockchainProof smart contract records the fingerprint under your wallet address with the block time. You get a public proof page and downloadable evidence.
Verify a proof
Select the original file or paste its SHA-256 fingerprint. The check reads the smart contract directly.
03 / Evidence Package
Evidence Package
Smart-contract record
The contract stores your fingerprint against your wallet address, with the block number and block time. Nobody, including BlockchainProof, can change or delete it.
Transaction details
The Arc transaction, block reference and contract address give anyone an independent way to inspect the record on ArcScan.
Evidence file
A downloadable JSON file lists the fingerprint, wallet, time, transaction and the exact contract call that re-checks the proof.
Printable certificate
Each public proof page prints as a certificate, or saves as a PDF from your browser's print dialog.
Store the original with the archive
The original file completes the evidence set: its fingerprint can be reproduced and matched to the signed manifest and public record whenever verification is needed.
03 / Examples
Use cases
Contracts, NDAs & deliverables
Record executed agreements, annexures, statements of work and delivered files to identify the exact version exchanged or signed.
Creative work & copyright
Timestamp drafts and final versions of manuscripts, photos, designs, music, video and other creative work to help establish prior existence and development history.
Software and source code
Record release archives, repository snapshots, firmware and technical documentation without publishing the underlying code.
Trade secrets & confidential know-how
Timestamp formulas, algorithms, methods, datasets and internal know-how before disclosure, sharing or dispute.
Corporate governance & compliance
Record policies, board materials, audits, risk assessments and regulatory documents to preserve exact versions and timelines.
Research, inventions, AI & datasets
Timestamp research records, invention disclosures, model files, datasets and development milestones to create a verifiable chronology.
Investigations & digital evidence
Timestamp emails, chats, photos, CCTV, logs, forensic images and investigation records to support integrity and chain of custody.
04 / Blockchain Evidence
Blockchain Evidence
Hangzhou Huatai v Shenzhen Daotong
The claimant used a third-party platform to capture an allegedly infringing webpage and anchor preservation data using Factom and Bitcoin. The Hangzhou Internet Court considered the source, collection process, generation and transmission path, technical verification and corroborating evidence.
Conclusion: Blockchain can provide a strong integrity and preservation layer when supported by a documented acquisition process.
China: Blockchain-Preserved Electronic Evidence
Chinese courts have recognised blockchain as a method for preserving and verifying electronic evidence.
Courts still examine the reliability of the collection, generation and preservation process. A blockchain timestamp does not by itself prove that the original information was true or authentic before it was recorded.
United States: Vermont Blockchain Evidence Law
Vermont law allows qualifying blockchain records to be self-authenticating when the statutory requirements are satisfied.
It can create presumptions regarding authenticity, time of recording and attribution, but does not automatically establish that the contents of the record are true or legally valid.
European Union: eIDAS Electronic Timestamps
Under eIDAS, an electronic timestamp cannot be denied legal effect or admissibility solely because it is electronic.
Qualified electronic timestamps receive stronger presumptions regarding the accuracy of the recorded time and the integrity of the data to which the timestamp is bound.
United States: Federal Evidence Rules
Blockchain records can be presented under existing US rules governing electronic evidence and authentication.
Their evidentiary value may be supported through evidence about the system or process used, digital identification, certifications, business records or expert testimony.
India: Bharatiya Sakshya Adhiniyam, 2023
Section 61 gives electronic and digital records the same legal effect, validity and enforceability as other documents, subject to Section 63.
Section 63 governs admissibility of electronic records and requires a certificate in applicable cases. The prescribed certificate includes the hash value of the electronic record, making cryptographic hashing directly relevant to electronic evidence.
04 / Common questions
FAQs
What is public?
The fingerprint, your wallet address, the time and the 1 USDC payment are recorded on Arc, which is a public blockchain. Your file is not.
What is in the evidence file?
The JSON file contains the fingerprint, wallet, time, network, contract, transaction and verification steps. It does not contain your original file, so keep the original safe.
Can I verify without this website?
Yes. The record lives in the smart contract, not on this website. Anyone can call getProof on the contract through ArcScan or any Arc node, or inspect the transaction directly.
What do I pay?
1 USDC per proof, plus a network fee of under 1 cent. Arc charges network fees in USDC, so USDC on Arc is all your wallet needs. Your wallet shows the exact fee before you approve.
How do I find my proofs later?
Select the original file in the verification tool, or connect the same wallet under My proofs.
Can I use a very large file?
There is no upload limit because the file stays on your device. Hashing currently loads the file into browser memory, so very large files may take longer or fail on devices with limited memory. You can instead calculate the SHA-256 hash separately and paste it.