# On-Chain Nonce Lookup

> On-Chain Nonce Lookup is a paid API for AI agents from x402-agent-store.rileycraig14.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-16).

Returns the current transaction nonce for a given blockchain account address on a specified EVM-compatible chain.

## Facts

- Endpoint: GET https://x402-agent-store.rileycraig14.workers.dev/chain/nonce
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/on-chain-nonce-lookup-b2c2a24a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_uU1cHVU4KmZomhjzWnZMn

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability on-chain-nonce-lookup-b2c2a24a
```

Example prompt: What's the current nonce for the address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Base?

## When to prefer this

Use this endpoint when an AI agent needs to determine the next transaction nonce for an EVM address before constructing or signing a transaction, or when verifying how many transactions an address has broadcast. Ideal for agents operating without API keys, paying per call in USDC via x402 on Base. Covers Base, Ethereum, Optimism, Arbitrum, Polygon, and Gnosis.

## Known failure modes

- Invalid or malformed address (non-0x format) — likely returns an error response
- Unsupported chain name — falls back to base or returns error
- Address not found on chain (zero nonce returned for new wallets) — valid response with nonce:0
- Payment failure via x402 — 402 response if USDC payment not provided
- Network/RPC timeout for the specified chain — service error

## How this service works

An address's transaction count (nonce) via eth_getTransactionCount — the next nonce to use and total outgoing transactions, across Base, Ethereum, Optimism, Arbitrum, Polygon, Gnosis. The read settlement and trading agents make to build and sequence transactions. Live public RPC; one paid call at $0.001.

## Output

A JSON object containing the chain name, the account address queried, and the current nonce (transaction count) as a number — e.g. {"chain":"base","nonce":1842,"address":"0x..."}. The nonce represents how many transactions have been sent from this address on the specified chain.

## Example request

```json
{
 "input": {
  "type": "http",
  "method": "GET",
  "queryParams": {
   "chain": "base",
   "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
  }
 }
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "chain": {
       "type": "string",
       "description": "base|ethereum|optimism|arbitrum|polygon|gnosis (default base)"
      },
      "address": {
       "type": "string",
       "description": "Account address (0x...)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "nonce": {
       "type": "number"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "base",
  "nonce": 1842,
  "address": "0x..."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/on-chain-nonce-lookup-b2c2a24a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-agent-store.rileycraig14.workers.dev](https://www.zero.xyz/host/x402-agent-store.rileycraig14.workers.dev/llms.txt)