ToolVet
78trust / 100

B20 Permit

by B20 Permit Inspector in Onchain & crypto

x402 APIPassing, checked 1 h ago

🆕 Every B20 has ERC-2612 permit built in — approve a spender by signature instead of a transaction. Reads exactly what an agent needs to build a valid permit: the token's DOMAIN_SEPARATOR, the owner's current nonce (so the signed payload can't be rejected/replayed), and the EIP-712 domain/type struct. Read-only — signs nothing.

GET
https://402.com.tr/api/x402/b20-permit
Price
$0.03
per call in USDC
Uptime
100%
last 30 days
Response time
457 ms
617 ms slowest 5%
Last check
Passed
1 h ago, next any minute now

Run a free test callHow to call it

Reliability

All checks passedSome failedAll failedNot checked

Status and outage history · Atom feed · Watch with other listings

How to call it

GET https://402.com.tr/api/x402/b20-permit

Each call costs $0.03 in USDC on Base, paid with the request over x402.

Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.

Example request

From the listing.

GET https://402.com.tr/api/x402/b20-permit?address=0xb20000000000000000000186a08e781c38059eec&owner=0x973a31858f4d2125f48c880542da11a2796f12d6

Parameters

ParameterTypeRequiredDescription
addressstringYesB20 token address
ownerstringNoOwner wallet (for the nonce, optional)

Example response

The provider's example. We can't check it without paying.

{
  "address": "0xb20000000000000000000186a08e781c38059eec",
  "checkedAt": "2026-10-11T17:18:26.333Z",
  "domainSeparator": "0xd4f8bd427e9fce6ac90676c1dbd0a5db5284c1397afa4e5e4a76925c5baac692",
  "isB20": true,
  "nonce": "0",
  "owner": "0x973A31858f4D2125f48C880542DA11a2796f12D6",
  "supportsPermit": true
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.03.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://402.com.tr/api/x402/b20-permit?address=0xb20000000000000000000186a08e781c38059eec&owner=0x973a31858f4d2125f48c880542da11a2796f12d6'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://402.com.tr/api/x402/b20-permit?address=0xb20000000000000000000186a08e781c38059eec&owner=0x973a31858f4d2125f48c880542da11a2796f12d6' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.03 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.03" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.03 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2F402.com.tr%2Fapi%2Fx402%2Fb20-permit
const res = await pay("https://402.com.tr/api/x402/b20-permit?address=0xb20000000000000000000186a08e781c38059eec&owner=0x973a31858f4d2125f48c880542da11a2796f12d6");
console.log(res.status, await res.text());
Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.03 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.03"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://402.com.tr/api/x402/b20-permit?address=0xb20000000000000000000186a08e781c38059eec&owner=0x973a31858f4d2125f48c880542da11a2796f12d6")
    print(res.status_code, res.text)

Security scan

No findings

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Recent checks

WhenResultHTTPTimePrice
1 h agoPassed402482 ms$0.03
6 h agoPassed402460 ms$0.03
11 h agoPassed402552 ms$0.03
15 h agoPassed402500 ms$0.03
20 h agoPassed402415 ms$0.03
Show 10 older checks
23 h agoPassed402617 ms$0.03
28 h agoPassed402468 ms$0.03
32 h agoPassed402437 ms$0.03
36 h agoPassed402390 ms$0.03
40 h agoPassed402487 ms$0.03
45 h agoPassed402562 ms$0.03
2 days agoPassed402620 ms$0.03
2 days agoPassed402457 ms$0.03
2 days agoPassed402452 ms$0.03
3 days agoPassed402473 ms$0.03