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OPENProof

Privacy Policy

OpenProof is designed so your files never leave your device. This policy explains how your information is handled. Last updated: July 4, 2026.

1. Our Commitment to Privacy

OpenProof is built around a core principle: your files never leave your device. The app is designed so that file hashing, receipt generation, and proof history all happen locally in your browser. No file content is ever uploaded, transmitted, or stored on any server. You are in control.

2. Local-First Data Model

OpenProof processes everything on your device through the browser File API and Web Crypto API. Here is what happens with each action:

  • File hashing: When you select a file, OpenProof reads it into browser memory, computes a SHA-256 hash, and discards the file contents. The hash computation is done entirely client-side.
  • Proof receipts: After registering a proof, OpenProof generates a JSON receipt locally and offers it as a download. Receipts are never stored on any server.
  • Proof history: Recent proof activity is saved only in your browser's localStorage. You can clear this at any time through your browser settings or by using the “Clear history” button in the app.

3. No Cloud, Sync, or Backup

OpenProof has no accounts, no backend, and no cloud infrastructure of its own. There is no sync across devices, no server-side storage, and no backup service. Blockchain registration is user-initiated through a connected wallet — it is a deliberate action, not an automatic sync.

4. What We Collect

OpenProof collects nothing. The app has no analytics, no telemetry, no tracking scripts, no cookies, and no server-side logging. There is nothing to opt out of because there is nothing to opt into.

The only data that leaves your device is a 32-byte SHA-256 hash that you deliberately submit to the OpenProofRegistry smart contract on Base Sepolia. The hash is a cryptographic fingerprint — it cannot be reversed to recover the original file. The transaction is public on the blockchain, which means the hash, the submitting wallet address, and the timestamp are visible to anyone.

When you connect a wallet through RainbowKit, the app can read your wallet address and chain ID. Your wallet provider (RainbowKit, WalletConnect, or your browser extension) manages your private keys. OpenProof never has access to your private keys, seed phrase, or any other wallet credentials.

5. Third-Party Services

OpenProof relies on the following third-party services:

  • Vercel: The app is hosted on Vercel as a fully static site. Vercel may collect standard server logs (IP address, request metadata) for operational purposes. See Vercel's privacy policy for details.
  • Base Sepolia blockchain: Proof registration transactions are submitted to the Base Sepolia testnet, a public blockchain. Transaction data is permanently public. Base is operated by the Base team (Coinbase).
  • RainbowKit & WalletConnect: Wallet connection is handled by RainbowKit and WalletConnect. These providers manage wallet discovery and connection flows. They may collect connection metadata as described in their respective privacy policies.

6. Data Deletion

Local data:Proof history stored in your browser’s localStorage can be cleared at any time through the app’s “Clear history” option or your browser’s storage settings.

Onchain data: Blockchain data is permanent by design. Once a transaction is accepted into a block, it cannot be deleted, modified, or undone. This is an intentional property of the proof-of-existence system — it ensures that a proof registered today remains verifiable indefinitely. If you do not want data onchain, do not register a proof.

7. Data Export

The only data OpenProof generates is your proof receipts. These are automatically offered as downloads when you register a proof and can also be exported from your proof history page at any time. Receipts are standard JSON files that you can save, back up, or transfer freely. OpenProof does not hold any of your data for export — it all stays with you.

8. Changes to This Policy

If this policy changes, the “Last updated” date at the top of this page will be revised. Material changes will also be noted in the repository changelog. Continued use of OpenProof after changes constitutes acceptance of the updated policy.

9. Contact

For privacy questions, open an issue on GitHub. For security concerns, see the project's security policy.