# OnchainExpat x402 Crypto Approval Checker

> OnchainExpat x402 Crypto Approval Checker is a paid API for AI agents from x402.onchainexpat.com, paid per call via x402, $0.04/call, status unknown (last checked 2026-09-15).

Checks whether a cryptocurrency token approval is valid, active, or potentially risky for a given wallet or contract

## Facts

- Endpoint: POST https://x402.onchainexpat.com/api/x402-crypto/approval-checker
- Price: $0.04/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/onchainexpat-x402-crypto-approval-checker-21d09b35
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_DgcOQa-CfObT8MgbCXZIJ

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 onchainexpat-x402-crypto-approval-checker-21d09b35 -d '<json body>'
```

Example prompt: Can you check if the USDC token approval I granted to the Uniswap V3 router contract (0xE592427A0AEce92De3Edee1F18E0157C05861564) is still active and whether the allowance amount looks risky for my wallet 0xAbCd1234...?

## When to prefer this

Use this endpoint when you need a quick pay-per-use check on a token approval's status without standing up your own blockchain RPC infrastructure. Ideal for DeFi security audits, wallet dashboards, or agent workflows that need to verify on-chain allowances on demand. Prefer this over building custom RPC calls when low-overhead, per-request billing via x402 is acceptable.

## Known failure modes

- Invalid or malformed contract/wallet address returns an error
- Unsupported blockchain network returns a not-supported error
- No approval found for the given pair returns empty or null allowance
- Network timeout or RPC node unavailability causes a service error
- Payment failure via x402 protocol results in 402 response before processing

## How this service works

Pay-per-request AI, crypto, proxy, and utility APIs using x402 protocol

## Output

Returns a JSON object with the current approval status, allowance amount, spender and token details, and potentially a risk flag indicating whether the approval is unlimited or otherwise potentially dangerous.

## Example request

```json
{
 "address": "0x1234567890123456789012345678901234567890"
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "address"
 ],
 "properties": {
  "chain": {
   "type": "string",
   "description": "Blockchain (default: ethereum)"
  },
  "address": {
   "type": "string",
   "description": "Wallet address (0x + 40 hex chars)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "type": "object",
   "properties": {
    "chain": {
     "type": "string"
    },
    "address": {
     "type": "string"
    },
    "approvals": {
     "type": "array",
     "description": "List of token approvals with spender, token, and amount"
    },
    "explorer_url": {
     "type": "string",
     "description": "Link to view wallet on block explorer"
    },
    "risk_assessment": {
     "type": "object",
     "description": "Risk level and recommendations"
    },
    "unlimited_approvals": {
     "type": "integer",
     "description": "Count of unlimited (max uint256) approvals"
    }
   }
  },
  "success": {
   "type": "boolean"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/onchainexpat-x402-crypto-approval-checker-21d09b35/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.onchainexpat.com](https://www.zero.xyz/host/x402.onchainexpat.com/llms.txt)