# 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 swap quote using the Allowance Holder contract to manage token allowances on 0x

## Facts

- Endpoint: POST https://agent.api.0x.org/v1/x402/swap-allowance-holder-quote/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-7c6433ab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_u8dXXo5soY42cD-Rnu5i2

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-7c6433ab -d '<json body>'
```

Example prompt: Get me a firm 0x swap quote to exchange 1 WETH for USDC on Ethereum mainnet using the Allowance Holder, with my wallet address 0xAbC123... as the taker and 0.5% max slippage.

## When to prefer this

Use this endpoint when you need a firm, executable quote (not just an indicative price estimate) for a token swap via 0x Protocol using the Allowance Holder contract for managing approvals. Prefer this over the indicative price endpoint when you are ready to actually execute a transaction and need guaranteed calldata. Choose this over Permit2-based endpoints when your integration specifically uses Allowance Holder for token approvals.

## Known failure modes

- Insufficient liquidity for the requested token pair returns an error or degraded quote
- Invalid or unsupported token addresses return a 400 bad request
- Unsupported chain ID results in an error response
- Quote expiry if not executed within the validity window
- Missing required query parameters such as sellToken, buyToken, or sellAmount return validation errors
- Slippage tolerance set too low may result in no available route

## Output

A firm, executable swap quote including the exact buy amount, guaranteed price, gas estimate, transaction calldata targeting the Allowance Holder contract, and routing details for the token swap. This quote is binding and can be submitted on-chain.

## 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-7c6433ab/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)