EIP-712 typed data hash and signature checker
Paste typed data (the JSON a wallet shows for signTypedData), and optionally a signature and the address you expect, to see the hashes and whether that address really signed it.
Try an example:EIP-712 Mail example
The page computes the encoded type, domain separator, message hash and final digest exactly as wallets do. With a signature it recovers the signer's address; with an expected address it tells you if they match.
This checks signatures that already exist. It never signs anything and never needs a private key. Both 65-byte and EIP-2098 compact signatures are accepted.
AI agents can run this through the SwapChan MCP tool typed_data_verify. Set up MCP
FAQ
- What can I use this for?
- Checking a permit, an order or a login message before you trust it: see what the digest commits to and which address signed it.
- Does it need my key?
- No. It only reads the typed data and a signature that already exists. Never paste a private key or seed phrase.
- What does low_s mean?
- Whether the signature uses the canonical low-s form most wallets and contracts require. A high-s signature can still recover an address but many contracts reject it.
- Is it safe?
- Yes. It only reads public data you paste. Nothing is stored or logged, and you never need a private key or seed phrase here.