akashi-notari

Akashi Notari — Simple Proof of Existence

Verify and timestamp any file on the blockchain in about a minute. Your file never leaves your computer; only a cryptographic hash is written on‑chain. Typical cost is around $1 (network fees may vary).

Website

• App: https://akashi-notari.com/
• Certificate retrieval: https://akashi-notari.com/certificate/

What you can do

• Create an on‑chain proof: Anchor your file’s SHA‑256 hash on supported networks with a single transaction.
• Keep your privacy: Hashing happens entirely in your browser. No file uploads, ever.
• Download a PDF certificate: Instantly receive a printable certificate containing the hash, timestamp, wallet, network, transaction link, and a QR code.
• Verify later, anywhere: Re‑generate the certificate at any time using just the transaction hash or block explorer URL.
• Multi‑network support: Use Base, Ethereum Mainnet, or Optimism (more coming soon).
• Wallets you already use: Connect via MetaMask or WalletConnect-compatible wallets.

How it works (at a glance)

1. Select a file. The site computes a SHA‑256 hash locally with a visible progress bar.
2. Connect your wallet. The app shows the current network and an estimated fee in the chain’s native token.
3. Click “Verify on chain.” The transaction writes the hash to the VerifierRegistry smart contract.
4. Download your PDF certificate. It includes a QR and direct link to the transaction/event log for future verification.

Certificate details

Each certificate includes:

• Filename (with safe normalization)
• SHA‑256 hash (FIPS 180‑4, 64 hex chars)
• Your wallet address
• Precise timestamp (UTC + Unix)
• Network name
• Transaction hash and a link to the explorer
• QR code linking to the transaction event log
• Simple instructions for independently recomputing and comparing the file hash in the future

Look up an existing proof

Already have a transaction? Open the Certificate page at https://akashi-notari.com/certificate/ and paste a transaction hash or full explorer URL to view registration details and download the certificate again.

Supported networks

• Base (primary)
• Ethereum Mainnet
• Optimism

Contract addresses

VerifierRegistry is the contract the web app writes to, paid in the chain's native token.

• Base: 0xeed9D0f7265892e84e43d05dA464c75add199260
  Explorer: https://basescan.org/address/0xeed9D0f7265892e84e43d05dA464c75add199260#code
• Ethereum: 0xeed9D0f7265892e84e43d05dA464c75add199260
  Explorer: https://etherscan.io/address/0xeed9D0f7265892e84e43d05dA464c75add199260#code
• Optimism: 0x859Fe07D2995875319b7e65592812392B16BBADe
  Explorer: https://optimistic.etherscan.io/address/0x859Fe07D2995875319b7e65592812392B16BBADe#code

VerifierRegistryUSDC is the contract for agents. It takes payment in USDC and stores the first anchor of each hash, so firstAnchor(hash) answers whether a file was notarised. Agents reach it over x402 or MCP at https://anchor.akashi-notari.com (see workers/anchor); one anchor costs 0.01 USDC. The web app does not write to it.

• Base: 0xe0C6bB0914be3E49e13fFBc389cF659871a1bCD3
  Explorer: https://basescan.org/address/0xe0C6bB0914be3E49e13fFBc389cF659871a1bCD3#code

Privacy & security

• Your document never leaves your device. Only the derived hash and transaction data are recorded on‑chain.
• No accounts, no uploads, no servers storing your files.

Disclaimer

This provides a cryptographic proof of existence only. It does not assess a document’s contents or legal validity. Store your original file safely to enable future verification.

Contact

Questions or feedback? Join the community on Discord: https://discord.gg/KBc44HTzP2