# Base Wallet Balance Lookup (x402)

> Base Wallet Balance Lookup (x402) 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 native ETH balance (in both ETH and wei) plus nonce and block number for a given Base wallet address, paid via USDC microtransaction over x402.

## Facts

- Endpoint: GET https://kr-x402-mvp.kgy5612.workers.dev/crypto/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-wallet-balance-lookup-x402-6699d643
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_DLETxReNDSK81UgArNarz

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-wallet-balance-lookup-x402-6699d643
```

Example prompt: What's the current ETH balance on Base for wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — show me the amount in ETH and the current nonce.

## When to prefer this

Choose this endpoint when your AI agent needs a lightweight, no-API-key way to check a Base wallet's native ETH balance, nonce, or current block height, and can pay $0.002 USDC per call via x402. Ideal for pre-flight gas checks, counterparty verification, and deposit confirmation in onchain agent pipelines. Prefer over free alternatives when you need guaranteed access without API key management and already have x402 payment infrastructure in place.

## Known failure modes

- Invalid wallet address format (must be 0x followed by 40 hex chars) returns a 400 or validation error
- Wallet address does not exist on Base — returns balance of 0 and nonce 0 (not an error, but may mislead)
- x402 payment failure if agent lacks sufficient USDC on Base returns a 402 Payment Required
- Base RPC node downtime could cause a 500 or timeout
- Missing required wallet query parameter returns a schema validation error

## How this service works

Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.

## Output

A JSON object containing: the current Base block number, chain identifier ('base'), the wallet's nonce (transaction count), the queried wallet address, ETH balance as a decimal float, and wei balance as a string. Useful for confirming wallet activity, gas availability, and deposit receipt.

## 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-wallet-balance-lookup-x402-6699d643/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)