Preflight any Base transaction before you sign it: simulates the call against latest st…

What it does

Preflight any Base transaction before you sign it: simulates the call against latest state (success or decoded revert reason), estimates gas with a safe limit, and prices the full fee (L2 execution + L1 data upper bound) in ETH and USD, plus the ETH balance needed. 0.50 USDC via x402 on Base.

Use with an agent

1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
2. Inspect. Fetch /resources/75773.json for the price and payment options.
3. Pay. Call GET https://preflight.madebydevx.com/v1/preflight. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
4. Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price

$0.5 / request

Protocol

x402 v2

Auth

No account or API key. Pay per request.

Networks

Base

x402 payment requirements

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xB3cDDccEe6B150c8efFD55B961afc0Ecefe7f247",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "500000",
    "amountUsd": 0.5,
    "maxTimeoutSeconds": 120
  }
]

Examples

curl "https://preflight.madebydevx.com/v1/preflight"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://preflight.madebydevx.com/v1/preflight");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://preflight.madebydevx.com/v1/preflight")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider

DevX Base Tx Preflight

Endpoint

https://preflight.madebydevx.com/v1/preflight

Machine-readable

/resources/75773.json