# 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 2026-10-15).

Returns a firm, executable quote for a token swap using the Allowance Holder contract to manage token approvals

## Facts

- Endpoint: GET https://agent.api.0x.org/v1/x402/swap-allowance-holder-quote/1?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/0x-swap-allowance-holder-firm-quote-d0fbbbd0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nfqHolTz8XUwsmeOnavU5

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-d0fbbbd0
```

Example prompt: Get me a firm 0x swap quote to trade 1000 USDC for ETH on Ethereum mainnet using the Allowance Holder, so I can see the exact execution price and transaction data before I submit.

## When to prefer this

Use this endpoint when you need a binding, executable swap quote rather than an indicative estimate — specifically when you intend to actually submit the transaction on-chain. Prefer this over the indicative price endpoint when you need calldata and Allowance Holder approval details. Choose this over direct DEX calls when you want 0x's DEX aggregation to optimize the route across multiple liquidity sources on Ethereum mainnet (chain ID 1).

## Known failure modes

- Insufficient liquidity for the requested token pair or amount returns an error or degraded quote
- Expired quote if too much time passes between fetching and submitting the transaction
- Invalid token addresses or unsupported pairs return 400 bad request
- Taker address not provided may result in incomplete calldata
- Network congestion may cause price to be unavailable momentarily
- Slippage tolerance too tight may result in no valid route found

## How this service works

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

## Output

Returns a firm, time-limited executable quote including the exact output token amount, swap price, gas estimate, transaction calldata, and any required Allowance Holder approval data needed to submit the swap 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-d0fbbbd0/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)