# Base ETH Balance & Nonce Lookup

> Base ETH Balance & Nonce Lookup is a paid API for AI agents from kr-x402-mvp.kgy5612.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).

Returns the live native ETH balance (in ETH and Wei) plus transaction nonce for a given wallet address on the Base blockchain.

## Facts

- Endpoint: GET https://kr-x402-mvp.kgy5612.workers.dev/crypto/eth-balance?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-eth-balance-nonce-lookup-2d08394d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-NL8oh3MsKln9_8NK9oDc

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 base-eth-balance-nonce-lookup-2d08394d
```

Example prompt: What's the current ETH balance and nonce for wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 on Base?

## When to prefer this

Choose this endpoint when you need real-time native ETH balance and nonce data for a Base wallet in a single lightweight call — especially for onchain AI agents doing pre-payment checks, self-monitoring, or counterparty verification on Base L2 specifically. Prefer this over general blockchain explorers when you need machine-readable JSON at $0.002/call via x402 micropayment, and when you specifically need the nonce alongside balance in one response.

## Known failure modes

- Invalid wallet address format (not matching ^0x[0-9a-fA-F]{40}$) returns an error
- Missing wallet query parameter returns a validation error
- Network or RPC unavailability may return a 5xx error
- Payment failure (insufficient USDC for x402 fee) blocks the request

## How this service works

Live native ETH balance + nonce for a wallet on Base: wallet=0x..

## Output

A JSON object containing the wallet address, native ETH balance as a decimal float and as a Wei string, the current transaction nonce (number of transactions sent), the block number at time of query, and the chain identifier ('base').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "wallet"
     ],
     "properties": {
      "wallet": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "examples": [
        "0xe4be4d0bd82d8e68203deff81f79ede0529f2617"
       ],
       "description": "Wallet"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "block": 53204016,
  "chain": "base",
  "nonce": 0,
  "wallet": "0xe4be4d0bd82d8e68203deff81f79ede0529f2617",
  "balance_eth": 0,
  "balance_wei": "0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-eth-balance-nonce-lookup-2d08394d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kr-x402-mvp.kgy5612.workers.dev](https://www.zero.xyz/host/kr-x402-mvp.kgy5612.workers.dev/llms.txt)