Featured app
Base Notary
An educational demo that records a file's unique fingerprint on Base so you can check later whether a file matches what was recorded. This is not a legal notary service.
Educational purposes only — not legal proof
Base Notary is a demonstration tool. It is not a legal notary service, legal framework, or substitute for professional legal advice. On-chain fingerprints are for learning and experimentation only and should not be considered proof in a court of law or accepted as official evidence by courts, employers, regulators, or other authorities.
Hash only — never opened or inspected
Your file is never opened or inspected in any way. We only compute a SHA-256 hash from the file bytes. The file itself is not saved on our servers or in your browser — only the hash and transaction link after you record it on Base.
Record a hash
- Choose the file you want to prove.
- Connect your wallet and pay a small USDC fee on Base.
- Save the transaction link for your own reference.
Verify File Hash On-Chain
- Upload the same file again.
- Paste the transaction link (or pick a saved proof from this browser).
- We compute a SHA-256 hash from your file and compare it to what is recorded on Base.
Uploads up to 25 MiB. Record: $0.1 per request. Verify: $0.01 per request. Your file is never opened or inspected in any way. We only compute a SHA-256 hash from the file bytes.
Educational use only. Base Notary is not a legal notary service or legal framework. Records here are not legal proof and should not be relied on in court or for official purposes.
Max 25 MiB. Your file is never opened or inspected in any way. We only compute a SHA-256 hash from the file bytes.
Choose a file to continue.
What happens to my file?
- Your file stays on your device until you submit.
- Your file is never opened or inspected — we do not read its contents, type, or meaning.
- We only compute a SHA-256 hash from the raw file bytes.
- Only that hash is written to Base — not the file itself.
- We do not store your file on our servers or in browser storage.
- After recording, this browser may save the transaction link and hash to help you verify later.