# 0x Swap Allowance Holder Firm Quote

> 0x Swap Allowance Holder Firm Quote is a paid API for AI agents from agent.api.0x.org, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Returns a firm (executable) quote for a token swap using the Allowance Holder contract to manage token allowances

## Facts

- Endpoint: GET https://agent.api.0x.org/v1/x402/swap-allowance-holder-quote
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/0x-swap-allowance-holder-firm-quote-ea89260b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_t9eJSQK79IqyCKui8XAOw

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 0x-swap-allowance-holder-firm-quote-ea89260b
```

Example prompt: Get me a firm, executable swap quote on 0x for selling 500 USDC to buy WETH on Ethereum mainnet — I need the actual calldata and allowance holder address so I can execute it right away.

## When to prefer this

Choose this endpoint over the indicative price sibling when you need an executable, binding quote with actual calldata to submit a transaction — not just an estimate for display purposes. Use when you are about to execute a swap and need precise output amounts, gas data, and allowance holder details. Prefer this when integrating with the Allowance Holder contract flow for managing ERC-20 token approvals.

## Known failure modes

- Insufficient liquidity for the requested token pair returns an error or empty route
- Invalid or unsupported token addresses return a 400 validation error
- Quote expires between fetch and execution, requiring a refresh
- Requested sell amount below minimum threshold returns an error
- Unsupported chain ID returns a 400 error
- Missing required query parameters return a 422 unprocessable entity error
- Payment not provided or insufficient USDC returns a 402 Payment Required

## How this service works

Get the firm quote for a swap using Allowance Holder to set allowances

## Output

A firm, executable swap quote including the exact output token amount, swap calldata, allowance holder contract address, price impact, gas estimate, and quote expiry — ready to submit as an on-chain transaction.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object"
    }
   },
   "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/0x-swap-allowance-holder-firm-quote-ea89260b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent.api.0x.org](https://www.zero.xyz/host/agent.api.0x.org/llms.txt)