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0x Swap Allowance Holder Firm Quote
x402
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 2026-10-16).
Returns a firm (executable) swap quote using the Allowance Holder contract to manage token allowances on the 0x protocol
Price / call$0.01
Success—
StatusUnknown
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, exchange rate, gas estimate, calldata for the swap transaction, the Allowance Holder contract address to approve, and any protocol fees — all guaranteed for a short validity window.
Example use cases
Best ETH-to-USDC swap rate
“I want to swap 2 ETH for USDC — can you get me a firm quote from 0x using the Allowance Holder contract so I know exactly how much USDC I'll receive before I approve and execute?”
On-chain arbitrage price check
“Get me a binding 0x Allowance Holder quote to swap 5000 USDC for WBTC on Ethereum — I need the guaranteed output amount and gas estimate to decide if this trade is worth executing.”
Portfolio rebalancing token swap
“I need to rebalance my wallet by swapping 500 LINK for DAI — fetch a firm 0x Allowance Holder quote so I can see the exact exchange rate and set my token allowance before submitting the trade.”
Technical details
Endpoint
GEThttps://agent.api.0x.org/v1/x402/swap-allowance-holder-quote/%2e%2e%2fswap%2fpermit2%2fquote?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a firm, executable swap quote (not just an indicative price) and want to use the Allowance Holder pattern instead of Permit2 for token approvals. Prefer this over the indicative price endpoint when you are ready to actually execute the swap and need guaranteed transaction data. Use over Permit2 quote when your integration or smart contract flow requires standard ERC-20 allowances rather than EIP-2612 signatures.
Side effects
- Insufficient liquidity for the requested token pair or amount returns an error or degraded quote
- Invalid or unsupported token address returns a 400 bad request
- Expired quote if the validity window lapses before execution
- Chain ID not supported by 0x Allowance Holder returns an error
- Missing required query parameters such as sellToken or buyToken returns a validation error
- Payment of $0.01 USDC via x402 protocol required; missing or failed payment returns 402
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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