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OnchainExpat x402 Crypto Approval Checker
x402
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 2026-09-13).
Checks whether a cryptocurrency token approval is valid, active, or potentially risky for a given wallet or contract
Price / call$0.04
Success—
StatusUnknown
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 use cases
DeFi security audit for active approvals
“I'm worried about my wallet security after connecting to a few different protocols last month. Can you scan my wallet and check which token approvals are still active, and flag any that look risky or have unlimited allowances that I should revoke?”
Verify contract spending before transaction
“I'm about to swap tokens on this new DEX platform but I want to make sure the smart contract address they're asking me to approve actually has reasonable token spending limits. Can you check what allowance amount it currently has for my USDT and whether it seems safe?”
Validate token allowance after wallet migration
“I just recovered my wallet on a new device and I'm not sure if my old token approvals for various DeFi protocols are still valid or what the current allowance amounts are. Can you verify the approval status for my DAI on the Aave lending contract so I know if I need to re-approve anything?”
Technical details
Endpoint
POSThttps://x402.onchainexpat.com/api/x402-crypto/approval-checkerWhen to prefer
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.
Side effects
- 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
Input
{
"address": "0x1234567890123456789012345678901234567890"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| chain | string | Blockchain (default: ethereum) |
| addressrequired | string | Wallet address (0x + 40 hex chars) |
Output
{
"data": {
"chain": "all",
"address": "0x1234567890123456789012345678901234567890",
"per_chain": {
"base": {
"summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chain_name": "Base",
"nft_approvals": [],
"erc20_approvals": [],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
]
},
"polygon": {
"summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chain_name": "Polygon",
"nft_approvals": [],
"erc20_approvals": [],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
]
},
"arbitrum": {
"summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chain_name": "Arbitrum",
"nft_approvals": [],
"erc20_approvals": [],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
]
},
"ethereum": {
"summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chain_name": "Ethereum",
"nft_approvals": [],
"erc20_approvals": [],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
]
},
"optimism": {
"summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chain_name": "Optimism",
"nft_approvals": [],
"erc20_approvals": [],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
]
}
},
"chains_scanned": [
"ethereum",
"base",
"arbitrum",
"polygon",
"optimism"
],
"recommendations": [
{
"action": "none_needed",
"message": "No immediate action required. Approvals look reasonable.",
"priority": "info"
}
],
"all_nft_approvals": [],
"all_erc20_approvals": [],
"cross_chain_summary": {
"overall_risk": "minimal",
"nft_approvals": 0,
"erc20_approvals": 0,
"total_approvals": 0,
"risk_description": "No significant approval risks detected across any chain",
"high_risk_approvals": 0,
"unlimited_approvals": 0
},
"chains_with_approvals": []
},
"cached": false,
"success": true,
"timestamp": "2026-06-18T05:54:50.072138+00:00"
}Schema · Response
| Field | Type | Description |
|---|---|---|
| data | object | |
| success | boolean |
Tags
x402
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