# Base Token Approval Check

> Base Token Approval Check is a paid API for AI agents from automaton-tx-explainer.vercel.app, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-18).

Checks all ERC-20 token approvals (allowances) granted by a given Base mainnet wallet address, identifying unlimited and non-zero approvals

## Facts

- Endpoint: GET https://automaton-tx-explainer.vercel.app/v1/base/approvals?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-token-approval-check-1373f7f1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZFzEQiHANDcPPoeMZZ8CD

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-token-approval-check-1373f7f1
```

Example prompt: Can you check what token approvals my Base wallet 0xAbC1234567890abcdef1234567890abcdef123456 has granted — specifically flag any unlimited allowances?

## When to prefer this

Use this endpoint when you need a quick, pay-per-call audit of ERC-20 token approvals on Base mainnet for a specific wallet address. It is particularly valuable for security reviews, pre-transaction risk checks, and DeFi onboarding flows where knowing which spenders have active allowances (especially unlimited ones) is critical. Prefer this over general blockchain explorers when you need structured, machine-readable approval data rather than a UI. Choose this over a full transaction explainer when the specific goal is allowance enumeration, not transaction decoding.

## Known failure modes

- Invalid or malformed wallet address (must match ^0x[0-9a-fA-F]{40}$) returns a validation error
- Address with no approvals returns an empty nonZeroApprovals array
- Payment failure or missing x402 USDC payment header returns 402 Payment Required
- Rate limiting or downstream Base RPC unavailability may cause transient 5xx errors
- Address with very large approval history may increase latency

## How this service works

Check a Base wallet's ERC-20 approvals: allowances for 8 major tokens (USDC, WETH, USDbC, DAI...) to common spenders (Permit2, Uniswap Universal Router, Uniswap SwapRouter02, Aerodrome Router...); flags unlimited approvals.

## Output

Returns the wallet owner address, total number of token-spender pairs checked, count of unlimited approvals, and a list of non-zero approvals each containing the token name, spender name, allowance amount, and a boolean indicating whether it is unlimited.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "owner": "0x...",
  "checkedPairs": 64,
  "unlimitedCount": 1,
  "nonZeroApprovals": [
   {
    "token": "USDC",
    "spender": "Permit2",
    "allowance": "unlimited",
    "unlimited": true
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-token-approval-check-1373f7f1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from automaton-tx-explainer.vercel.app](https://www.zero.xyz/host/automaton-tx-explainer.vercel.app/llms.txt)