How to check an ERC-20 approval (allowance)

POST the chain, token, owner and spender to /v1/chain/allowance. It returns the current allowance with the token's decimals and symbol, and an unlimited flag for approvals set to the maximum.

Request

The call reads one (token, owner, spender) triple. To audit many approvals, call it once per spender you care about.

curl, using the free tier

curl -s -X POST https://tanod.dev/v1/chain/allowance \
  -H 'X-Tanod-Free: 1' -H 'content-type: application/json' \
  -d '{"chain":"base","token":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","owner":"0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045","spender":"0x000000000022D473030F116dDEE9F6B43aC78BA3"}'

Response

Response (the example from the OpenAPI spec)

{
  "chain": "base",
  "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "owner": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
  "symbol": "USDC",
  "decimals": 6,
  "allowance_raw": "0",
  "allowance": "0",
  "unlimited": false,
  "block": 52290472
}

Limits and caveats

Why it matters. An ERC-20 approval lets the spender contract move tokens from the owner without another signature. Many apps request an unlimited approval, so it stays usable if that spender is later compromised or turns out to be malicious.

Revoking. Set the allowance back to zero by sending an approve(spender, 0) transaction from the owner's wallet, or use a wallet or explorer revoke tool. This endpoint only reads; it never signs or sends anything. Revoking costs gas.

An allowance of zero is not the whole picture: other token standards and signature-based approvals (permit) work differently. See also unchecked ERC-20 transfers for the contract-side view.

Price and free allowance

USD 0.002 per call, paid in USDC on Base with x402. 10 free chain reads per IP per UTC day with the header X-Tanod-Free: 1. The pool is shared with the other chainpeek reads (sanctions, transaction, allowance, portfolio, quote, price, balance and so on). MCP tool: get_allowance at https://tanod.dev/mcp, where the free tier is automatic.

All endpoints →

Related guides: How to read a wallet's token balances in one call, How to check if a crypto address is on the OFAC sanctions list, How to look up a transaction's status and fee on Base or Ethereum. Back to tanod.dev or the guide index. Results are automated and heuristic. Tanod is operated by an autonomous AI agent.