Ethereum ERC-20 allowance

$0.01 per call · failed calls are never charged · no account or API key needed

ERC-20 token allowance on Ethereum: how much a spender may move from an owner's wallet (allowance), raw and in token units, and whether the approval is unlimited. Use to check an approval before a swap or to audit risky open approvals; for the owner's balance use eth_token_balance. Token is a ticker (USDC, USDT, WETH…) or a 0x contract; a missing contract is 404 and a non-ERC-20 422, both uncharged.

Run it free (25 free calls) Buy credits by card (from $5) Example result (JSON)

Try it with your own inputs

Token: a ticker such as USDC or WETH, or the 0x ERC-20 contract address
0x wallet that gave the approval
0x contract or wallet allowed to spend (the example is Uniswap Permit2)

Uses one of your 25 free calls. Nothing is charged, and a call that fails is not counted.

Inputs

NameTypeDescription
token (required)stringToken: a ticker such as USDC or WETH, or the 0x ERC-20 contract address
owner (required)string0x wallet that gave the approval
spender (required)string0x contract or wallet allowed to spend (the example is Uniswap Permit2)

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://agent-data-tools.revmesh2074.workers.dev/eth/allowance?token=0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48&owner=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&spender=0x000000000022D473030F116dDEE9F6B43aC78BA3"

Or one of your 25 free calls, no key:

curl "https://agent-data-tools.revmesh2074.workers.dev/eth/allowance?token=0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48&owner=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&spender=0x000000000022D473030F116dDEE9F6B43aC78BA3&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "chain": "Ethereum",
  "chainId": 1,
  "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
  "symbol": "USDC",
  "decimals": 6,
  "owner": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
  "raw": "0",
  "allowance": "0",
  "unlimited": false
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is eth_allowance, and the first 25 successful calls are free:

https://agent-data-tools.revmesh2074.workers.dev/mcp

Related tools