Security · x402 · early usage

Allowance check on Arc, before an app asks for an approval: what owner has already appr…

by apexfaucet.xyz · discovered, not yet claimed by its owner · updated 2026-10-10

30d calls2

30d payers2

MethodGET

Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

Allowance check on Arc, before an app asks for an approval: what owner has already approved to spender for a token (default USDC; add &token=0x... for another), in tokens and USD, whether it is unlimited, the owner's balance, whether the spender is a contract and its name if it is one our own code uses on Arc (Uniswap v4 PoolManager, UniversalRouter, Permit2, Circle Gateway Wallet, CCTP TokenMessenger, the launchpad router; never guessed), and risk signals (unlimited to an unknown contract, an…

Tags: allowance · approval check · erc20 · arc · usdc · bazaar

Call contract

Method: GET
Input: query parameters
Output: json
Last paid call: 2026-10-10

Input example from Bazaar metadata

{
  "owner": "0x024b82335C29Fa5606a8ea5c1D24FC9eAD50700C",
  "spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3"
}

Output example

{
  "data": {
    "allowance": null,
    "allowanceRaw": "115792089237316195423570985008687907853269984665640564039457584007913129639935",
    "isUnlimited": true,
    "ok": true,
    "owner": "0x024b82335c29fa5606a8ea5c1d24fc9ead50700c",
    "ownerBalance": 0.44577,
    "riskSignals": [
      "unlimited approval (to Permit2 (Uniswap))"
    ],
    "spender": "0x000000000022d473030f116ddee9f6b43ac78ba3",
    "spenderName": "Permit2 (Uniswap)",
    "symbol": "USDC",
    "token": "0x3600000000000000000000000000000000000000",
    "usdValue": null
  },
  "ok": true,
  "paid": 0.001
}

Use with an agent

Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
Inspect. Fetch /resources/51547.json for the price and payment options.
Pay. Call GET https://apexfaucet.xyz/api/x402/arc-allowance. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, eip155:5042, Solana, eip155:56, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price: $0.001 / request
Protocol: x402 v2
Auth: No account or API key. Pay per request.
Networks: Base, eip155:5042, Solana, eip155:56
Demand: 2 calls · 2 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

Scheme	Network	Asset	Amount	Pay to	Timeout
exact	Base eip155:8453	USDC	$0.001	0xd334ab5151c624cada654854e2879903dc4217ed	300s
exact	eip155:5042 eip155:5042	0x3600000000000000000000000000000000000000	1000	0xd334ab5151c624cada654854e2879903dc4217ed	300s
exact	eip155:5042 eip155:5042	0x3600000000000000000000000000000000000000	1000	0xd334ab5151c624cada654854e2879903dc4217ed	604900s
exact	Base eip155:8453	USDC	$0.001	0xd334ab5151c624cada654854e2879903dc4217ed	604900s
exact	Solana solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp	USDC	$0.001	HYiepS7mNCVVKoaDmZLQ6rNtMWHTQqKheM1NLGn1x8kJ	300s
exact	eip155:56 eip155:56	0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d	10000000000000000	0xd334AB5151C624cAdA654854E2879903Dc4217eD	300s
exact	eip155:56 eip155:56	0xcE24439F2D9C6a2289F741120FE202248B666666	10000000000000000	0xd334AB5151C624cAdA654854E2879903Dc4217eD	300s

accepts[] (raw JSON)

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xd334ab5151c624cada654854e2879903dc4217ed",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:5042",
    "payTo": "0xd334ab5151c624cada654854e2879903dc4217ed",
    "asset": "0x3600000000000000000000000000000000000000",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:5042",
    "payTo": "0xd334ab5151c624cada654854e2879903dc4217ed",
    "asset": "0x3600000000000000000000000000000000000000",
    "amount": "1000",
    "maxTimeoutSeconds": 604900
  },
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xd334ab5151c624cada654854e2879903dc4217ed",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 604900
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "HYiepS7mNCVVKoaDmZLQ6rNtMWHTQqKheM1NLGn1x8kJ",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:56",
    "payTo": "0xd334AB5151C624cAdA654854E2879903Dc4217eD",
    "asset": "0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d",
    "amount": "10000000000000000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:56",
    "payTo": "0xd334AB5151C624cAdA654854E2879903Dc4217eD",
    "asset": "0xcE24439F2D9C6a2289F741120FE202248B666666",
    "amount": "10000000000000000",
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)

{
  "type": "object"
}

Example shape — generated from the schema, not a captured live response

{}

Examples

curl

curl "https://apexfaucet.xyz/api/x402/arc-allowance"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

JavaScript

const res = await fetch("https://apexfaucet.xyz/api/x402/arc-allowance");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

Python

import httpx
res = httpx.get("https://apexfaucet.xyz/api/x402/arc-allowance")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider: apexfaucet.xyz
Endpoint: https://apexfaucet.xyz/api/x402/arc-allowance
Machine-readable: /resources/51547.json