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Account Nonce Lookup (EVM)
x402
Account Nonce Lookup (EVM) is a paid API for AI agents from agent402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Returns the transaction count (nonce) of an EVM account address as both decimal and hex, optionally scoping to pending mempool state.
Price / call$0.001
Success—
StatusUnknown
How this service works
The transaction count of an account, which is the nonce its next transaction must carry. Ask for block "pending" to include transactions already in the mempool, which is what you want before signing; the default "latest" counts only mined transactions. Returns the count as a decimal string and as hex. EVM chains: ethereum, base, polygon, arbitrum, optimism.
Output
A JSON object containing the queried address, the network, the block tag used, the transaction count as a decimal string (nonce), and the same value as a hex string (nonceHex). Example: {"address":"0xabf4...","network":"base","block":"latest","nonce":"412","nonceHex":"0x19c"}.
Example use cases
Pre-signing nonce check on Base
“Before I sign and broadcast this transaction, get me the pending nonce for 0xabf4fabd7c416fb67202e5f9002389fc75e2a9d0 on Base so I set the right sequence number.”
Ethereum wallet transaction count audit
“How many transactions has 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 sent on Ethereum mainnet? Give me the latest mined count.”
Arbitrum nonce for multisig coordinator
“Fetch the current nonce for 0x1234567890abcdef1234567890abcdef12345678 on Arbitrum — I need to coordinate the next nonce across multiple signers.”
Technical details
Endpoint
GEThttps://agent402.tools/api/chain/nonceWhen to prefer
Use this endpoint when you need the transaction count / nonce for an EVM account before constructing or signing a transaction, especially with block=pending to capture in-flight mempool transactions. Prefer it over general block explorer APIs when you need both decimal and hex nonce quickly with a simple GET call across multiple EVM chains (Ethereum, Base, Polygon, Arbitrum, Optimism).
Side effects
- Invalid or malformed address returns an error response
- Unsupported network name returns an error
- Invalid block tag value returns an error
- Network RPC node unavailability causes a timeout or 5xx error
- Address with zero transactions returns nonce 0 (not an error, but may be unexpected)
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"block": "latest",
"nonce": "412",
"address": "0xabf4fabd7c416fb67202e5f9002389fc75e2a9d0",
"network": "base",
"nonceHex": "0x19c"
}
}Tags
x402
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