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402Sentinel x402 Counterparty Risk Firewall
x402
402Sentinel x402 Counterparty Risk Firewall is a paid API for AI agents from 402sentinel.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).
Scores an x402 payment counterparty address (0-100 risk) and returns an allow/review/block decision based on on-chain settlement behaviour before payment is made
Price / call$0.002
Success—
StatusUnknown
How this service works
Buyer-side payment firewall: should THIS agent make THIS payment now? Where /api/assess vets the seller, this vets the payment against your own agent's behaviour. POST {agent_id, payment:{payto_address,amount,resource_url}, context?:{untrusted_text,intended}, policy?} returns allow/hold/block plus 9 signals incl. routing_anomaly, velocity, amount_anomaly, injection_destination, intent_mismatch. Stateful per agent_id.
Output
A JSON response containing a 0-100 risk score and a categorical decision of allow, review, or block, derived from on-chain signals including address age, facilitator-aware payer diversity, and settlement maturity for the queried counterparty address.
Example use cases
Validate vendor before automated USDC payments
“I'm about to set up recurring micropayments to this service provider's x402 address on Base. Can you quickly check if they're legitimate and safe to pay based on their on-chain history, and let me know if I should allow it or flag it for review first?”
Screen suspicious payment endpoint for fraud
“An agent just tried to pay this unknown x402 endpoint that popped up in our workflow. Run a risk check on that address and tell me if it looks legitimate or if we should block it — I'm worried it might be a scam endpoint trying to intercept our payments.”
Gate RWA token transfers to trusted counterparties
“Before my agent transfers this tokenized asset to a buyer's x402 address, verify they're a legitimate counterparty and not flagged for sanctions or structuring issues. Give me the risk score and your recommendation on whether we should proceed.”
Technical details
Endpoint
POSThttps://402sentinel.com/api/firewallWhen to prefer
Use this endpoint when an AI agent is about to make an x402 micropayment and needs a pre-flight counterparty risk check based purely on on-chain settlement behaviour. Prefer this over generic blockchain analytics when you specifically need x402-aware payer diversity signals and a structured allow/review/block decision without any signup or API key.
Side effects
- Address not found on-chain — insufficient history to score, may return a default high-risk or indeterminate result
- Invalid or malformed address input — 400 error
- Payment for the x402 call itself fails or is rejected — service not invoked
- Network congestion on Base causing delayed settlement verification
- New address with zero history — may default to block or review due to lack of data
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| policy | object | Optional checks, e.g. {check_counterparty: true}. |
| context | object | Where the payment instruction came from (provenance). |
| payment | object | The payment instruction being vetted. |
| agent_id | string | The calling agent's wallet (keys per-agent history). Optional — auto-filled from the x402 payer if omitted. |
Tags
x402
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