Cryptographic proof for files, built on Base.
OpenProof lets you timestamp a file fingerprint onchain without uploading the file anywhere.
This MVP uses Base Sepolia testnet. No real funds are required.
OpenProofRegistry
Base Sepolia testnet
research-notes.pdf
Local file - never uploaded
SHA-256 fingerprint
0x8b6f2b9c3b1e4f6c8897d29d39e45e4ff34b955cf9e693c8127a92f8ac7f54a1
Five steps. No file upload.
OpenProof keeps the file local, registers only the fingerprint, and leaves verification public.
Select file
Choose a local file in the browser.
Hash locally
Generate a SHA-256 fingerprint.
Connect wallet
Use a wallet on Base Sepolia.
Register proof
Write the fingerprint onchain.
Verify later
Match the exact file again.
Built for repeated proof workflows.
OpenProof v0.x adds local history, receipt validation, shareable proof pages, QR verification, and deterministic bundle proofs without adding accounts, storage, or a backend.
Local history
Recent proofs stay in this browser only.
Receipt import
Validate downloaded JSON against Base Sepolia.
Proof pages
Open a shareable /proof/[hash] URL.
QR verify
Download a QR code for proof pages.
Bundles
Register one deterministic hash for many files.
Why files never leave your browser.
OpenProof uses the browser File API and Web Crypto API. The app does not need a backend, storage bucket, database, or IPFS service for the core proof flow.
A matching hash was registered on Base Sepolia.
OpenProof proves that a wallet registered a matching file fingerprint at a contract timestamp. Verification only works for an exact file match.
OpenProof does not prove ownership, authorship, legal validity, or the truth of a file's contents. It proves a matching hash was registered by a wallet at a certain time.
Deployed registry contract.
Base Sepolia keeps the MVP testable without real funds. Base mainnet deployment is a future roadmap item.
Registry address
0x60d3DD631E6e4F6D76f761689d6FA229945a874a