Privacy-first proof-of-existence for files.
Timestamp file fingerprints on Base Sepolia without uploading a single byte.
| Create proof | Verify proof |
|---|---|
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OpenProof creates verifiable timestamps for file hashes. No uploads. No accounts. No database. Select a file, hash it locally with SHA-256, register only the hash on Base Sepolia, and download a portable JSON receipt. Verify later by hashing the exact same file again — no original file ever leaves your device.
| Feature | Description |
|---|---|
| Local SHA-256 hashing | Files are hashed in-browser via the Web Crypto API. File bytes stay local. |
| Proof registration | Register bytes32 hashes on the Base Sepolia blockchain. |
| Proof verification | Re-hash local files and check against the onchain registry. |
| JSON receipts | Portable, versioned proof receipts downloaded locally. |
| Receipt import | Validate existing receipts and verify hashes onchain. |
| Local proof history | Recent proofs stored in browser local storage only. |
| Public proof pages | /proof/[hash] reads public registry state for sharing. |
| QR verification | QR-encode the proof page URL for quick mobile verification. |
| Bundle proofs | Deterministic combined hash for multiple local files. |
- Researchers — timestamp research data and preprints.
- Creators — prove ownership of digital works without uploading.
- Archivists — anchor file fingerprints to an immutable chain.
- Anyone — who needs to prove a file existed at a certain time.
"Proof before platform — let users verify existence without surrendering the file itself."
OpenProof is part of a broader direction: software that helps people prove things without surrendering the thing itself. Local-first by default. Privacy before convenience theatre. Permanence without exposure.
| Version | Date | Highlights |
|---|---|---|
| v0.4.0 | 2026-06 | Receipt specification — canonical JSON receipt format with deterministic serialization |
| v0.3.0 | 2026-05 | Bundle proofs — combined hash for multiple files with sorted commitments |
| v0.2.0 | 2026-04 | QR verification — encode proof page URL for mobile verification |
| v0.1.0 | 2026-03 | MVP — basic proof creation, verification, and local history |
- Live app
- BaseScan contract
- Development setup
- Architecture
- Deployment
- Testing
- Contributing
- Receipt specification
- Threat model
- Privacy policy
- Terms of service
- Changelog
AGPL-3.0-only. See LICENSE.
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| OpenProof (you are here) | Privacy-first proof-of-existence |