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Base Toolbox Uniswap v3 Preflight Check
x402
Base Toolbox Uniswap v3 Preflight Check is a paid API for AI agents from basetoolbox.cartonpliant.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).
Validates a Uniswap v3 swap on Base before signing — checks token sellability, expected output amount, and warnings about the transaction.
Price / call$0.1
Success—
StatusUnknown
How this service works
Base toolbox: before you sign on Base — Uniswap v3 preflight, leftover allowances, tx explain, transfer check. $0.10 USDC. Also $0.001 price/gas/ENS. GET /v1/constants free. No CoinGecko key.
Output
A JSON object indicating whether the swap is safe to proceed (ok), the recommended next action (next), expected output amount (amountOut), minimum acceptable output (minOut), whether the token is sellable (sellable), and an array of any warnings about the transaction.
Example use cases
Safe swap validation before signing
“I'm about to swap 500 USDC for WETH on Uniswap v3 on Base — can you run a preflight check first and tell me the expected output amount, the minimum I'd get, and whether there are any warnings I should worry about?”
Check token sellability on Base
“Is PEPE actually sellable on Uniswap v3 on Base right now? Run a preflight before I try to swap it — I don't want to sign a transaction that's going to fail.”
Verify allowance and swap output before trade
“I want to swap 1000 DAI to USDC on Base via Uniswap v3 — check my leftover allowances and simulate the swap so I know what I'd receive before I approve anything.”
Technical details
Endpoint
POSThttps://basetoolbox.cartonpliant.workers.dev/v1/preflightWhen to prefer
Choose this endpoint when you need to validate a Uniswap v3 swap on Base chain before the user signs — particularly when you want to surface warnings, confirm token sellability, or calculate expected output without executing a transaction. Prefer this over on-chain simulation when you want a cheap ($0.10 USDC), fast, pre-packaged preflight that also checks allowances and explains the transaction.
Side effects
- Token not tradeable on Uniswap v3 Base — sellable: false
- Insufficient liquidity for the requested trade size
- Payment not received or invalid USDC payment — 402 response
- Malformed input object missing required swap parameters
- Slippage or price impact too high — warning in warnings array
- Token contract address not recognized on Base network
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"next": "swap",
"minOut": "…",
"sellable": true,
"warnings": [],
"amountOut": "…"
}
}Tags
x402
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