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SignGate x402 Transaction Preflight – Agent Buyer Identity & Purchase Governance
x402
SignGate x402 Transaction Preflight – Agent Buyer Identity & Purchase Governance is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-13).
Checks whether an AI agent's buyer identity and wallet are eligible to purchase a specific x402-priced API, dataset, or tool before committing payment.
Price / call$0.25
Success—
StatusUnknown
How this service works
Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.
Output
Returns a JSON object containing the network (e.g. eip155:8453 for Base), product identifier, an assessment object with a numeric risk_score, a risk_level string (e.g. 'low'), and a flags array listing any policy violations or concerns. May also include identity, activity, and provenance sub-objects describing the buyer and merchant.
Example use cases
Agent spending guard before API purchase
“Before my agent pays the x402 fee for that LLM inference API at merchant 0x1a2b3c4d5e6f7890aabbccddeeff00112233445566, check whether my wallet 0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef is eligible and the risk is low — expected amount is 1.50 USDC.”
Sensitive dataset purchase compliance check
“My agent wants to buy access to a health dataset at contract address 0xAABBCC1122334455667788990011AABBCCDDEEFF from merchant 0x9988776655443322110099887766554433221100 for 5.00 USDC — run the preflight to verify the buyer identity fits and there are no policy flags before it proceeds.”
Autonomous agent fleet purchase governance
“Before any agent in my fleet spends on x402 tools, screen this purchase: merchant is 0x0011223344556677889900AABBCCDDEEFF001122, spender wallet is 0xFFEEDDCCBBAA99887766554433221100FFEEDDCC, expected amount 0.50 — flag anything risky so I can decide whether to approve.”
Technical details
Endpoint
GEThttps://base-agent-preflight.bytoken2023.workers.dev/v1/x402/transaction/preflightWhen to prefer
Use this endpoint when an AI agent is about to autonomously execute an x402 micropayment and you need a governance gate — specifically to validate buyer identity fitness, policy compliance, and risk before committing funds. Prefer this over generic allowance checks when the product category, sensitivity, or price tier requires structured approval policy enforcement. Best suited for agentic pipelines where spending decisions must be auditable.
Side effects
- Missing required merchant_address query parameter returns a validation error
- Invalid Ethereum address format (not matching 0x[40 hex chars]) causes parameter rejection
- Unrecognized wallet or merchant on-chain may return incomplete identity/provenance data
- Network congestion or RPC errors may cause slow or failed on-chain lookups
- High risk_score or non-empty flags array means the purchase should not proceed
- Service unavailable on Cloudflare Worker edge returns HTTP 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"network": "eip155:8453",
"product": "x402-transaction-preflight",
"assessment": {
"flags": [],
"risk_level": "low",
"risk_score": 0
}
}
}Tags
x402
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