[ NEURALARC_REFERENCE_BUILD_—_CHAINVERIFY ]
Blockchain Document Verification Infrastructure
What it is
Documents anchored to a blockchain by their SHA-256 hash, so anyone can verify a file is the exact version that was registered — without the document ever being public.
[ THE_PROBLEM ]
Why this existed
Documents move between investors, lawyers, auditors, financial institutions and regulators — and storage systems can say where a file lives, but not whether it is the original, whether it existed at a point in time, or whether it was quietly replaced by a newer version. Verification currently runs on trust in whoever sent the file.
[ WHAT_WE_BUILT ]
What we built
A document registration and verification platform that anchors cryptographic fingerprints rather than files. Registering a document hashes it (SHA-256) and writes the hash plus document ID, issuer wallet, timestamp, version and status to a Solidity registry contract on a Polygon/Base/Ethereum-compatible network, storing the transaction ID — the document itself stays off-chain in encrypted S3-compatible storage, so nothing confidential is exposed and on-chain storage costs stay negligible. Verification re-hashes whatever file is uploaded and compares it against the on-chain record: an exact match proves the document is unmodified since registration, a mismatch proves the opposite. Every registered document gets a QR code opening its verification record, embeddable in property documents, certificates, contracts, reports or printed copies. Documents version rather than replace — an amended agreement is a new immutable hash linked to the same document record through a previous-version pointer — so full history is preserved and outdated versions can be revoked without losing the record of them. Assets get vaults: a property data room of title documents, sale agreements, valuation reports, legal opinions, inspection reports and compliance certificates, each individually verified, with a dashboard showing the verification status of the whole collection. Issuers manage categories, versions, document-to-asset assignment, verification links and QR generation from a central dashboard; every registration links to its blockchain transaction so transaction, block, contract, timestamp and issuing wallet can be checked on a public explorer without trusting the platform at all. Access runs in four tiers — super admin, organisation admin, verifier, public — with per-document public-verification flags, plus an optional verification-history audit trail. Next.js front end, Node.js/Next.js APIs, PostgreSQL.
- SHA-256 fingerprinting of every registered document
- Hash anchored to a Solidity registry contract with document ID, issuer wallet, timestamp, version and status
- Documents kept off-chain in encrypted S3-compatible storage — nothing confidential becomes public
- Verification by re-hashing an uploaded file and matching it against the on-chain record
- QR code per document opening its verification record, embeddable in printed documents
- Version chains — each version gets its own immutable hash linked to the same document record
- Asset vaults grouping title documents, agreements, valuations and certificates per property
- Issuer dashboard for categories, versions, revocation, verification links and QR generation
- Independent verification via public block explorers: transaction, block, contract, timestamp, issuer wallet
- Four access tiers — super admin, organisation admin, verifier, public — with per-document public flags
- Optional verification-history audit trail of who checked which document, and when
[ HOW_IT_IS_USED ]
How a company uses it
A real-estate platform, registrar, custodian or issuer lets any counterparty confirm the sale agreement, valuation report or certificate they are holding is the exact version registered on-chain — by scanning a QR code rather than trusting the file they were sent.
Built with
[ COMMON_QUESTIONS ]
Questions clients ask
Is the document itself stored on the blockchain?
No — only its SHA-256 hash. The document stays in encrypted off-chain storage; the chain holds a fingerprint that uniquely identifies the exact bytes registered. That preserves confidentiality, keeps on-chain storage costs negligible, and still lets anyone holding the original file prove it matches the registered version.
What happens when a document is amended?
The amended file is registered as a new version: it gets its own hash and its own transaction, linked to the same document record through a previous-version pointer. Nothing is overwritten — the complete version history stays queryable, and outdated versions can be revoked without losing the record of them ever having existed.
Who can verify a document?
That depends on the document's flags. Documents marked for public verification can be checked by anyone holding the file plus the QR code or link; restricted documents verify only for authorised verifiers. In every case the result — exact match or mismatch — comes from comparing a freshly computed hash against the on-chain record, not from trusting the platform.
[ RELATED_WORK ]
Similar builds
NeuralArc reference build — YieldX
Tokenised Revenue-Sharing Platform
Fractional investment in revenue-generating assets, with a blockchain underneath doing the ownership, eligibility and distribution accounting.
Read case studyNeuralArc reference build — EquityLedger
Blockchain Cap Table & Ownership Platform
Company and SPV ownership run as a programmable ledger — every issuance and transfer is a transaction, and the cap table can be reconstructed for any past date.
Read case studySME retail & distribution
Billing Workspace with an Embedded Copilot
A billing app where the assistant can actually operate the app, not just describe it.
Read case studyIs this close to your problem?
Most engagements start with a version of something on this page. Tell us what is different about yours and we will tell you what it changes.
Start a conversation