# ERC-20 Allowance Checker with Balance and Sufficiency Verdict

> ERC-20 Allowance Checker with Balance and Sufficiency Verdict is a paid API for AI agents from api.x-402.online, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-03).

Returns the ERC-20 allowance granted by an owner to a spender (USDC by default), along with the owner's token balance and a sufficiency verdict if a target amount is provided.

## Facts

- Endpoint: GET https://api.x-402.online/v1/chain/allowance?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-03
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc-20-allowance-checker-with-balance-and-sufficiency-verdict-dba0ebb7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IbtmdSRI-1GC7GE9lsi3I

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability erc-20-allowance-checker-with-balance-and-sufficiency-verdict-dba0ebb7
```

Example prompt: Check if the spender contract 0xABC...123 has enough USDC allowance to pull 200 USDC from wallet 0xDEF...456 on Base — and tell me the current balance and whether the allowance is sufficient.

## When to prefer this

Use this endpoint when an AI agent or workflow needs to verify on-chain ERC-20 approval status before attempting a transferFrom or similar pull-payment operation — especially for USDC on Base. It combines three checks (allowance, balance, sufficiency) in a single call, avoiding multiple RPC round-trips. Prefer it over raw RPC calls when you need a human-readable verdict without writing blockchain query code.

## Known failure modes

- Invalid or malformed owner/spender address returns a 400 error
- Unsupported chain ID or token contract returns an error or empty result
- RPC node unavailability causes a 503 or timeout
- Missing required query parameters (owner, spender) returns a 422 validation error
- Amount parameter provided in wrong format may be ignored or cause parsing error

## How this service works

Get an ERC-20 allowance with the owner's balance and a sufficiency verdict for the amount you plan to pull. ERC-20 allowance of a spender on an owner (USDC by default), with the owner's balance and, if you pass ?amount=, a verdict: i…

## Output

Returns the current ERC-20 allowance (in token units and human-readable), the owner's token balance, the token metadata (symbol, decimals), and — if an amount was supplied — a boolean sufficiency verdict indicating whether the allowance covers the requested amount.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-20-allowance-checker-with-balance-and-sufficiency-verdict-dba0ebb7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x-402.online](https://www.zero.xyz/host/api.x-402.online/llms.txt)