x402-safe

Verify a counterparty before you pay it on x402.

78% of everything paid on x402 is an unverifiable ghost — a wallet exactly one other wallet has ever paid. Your agent is about to send real USDC to one of them. x402-safe checks AgentRank at the moment a server answers 402, and blocks the payment if the recipient is not a real, settlement-backed agent.

It is zero-dependency and client-agnostic: you keep your x402 payment library, x402-safe just gates it.

Install

npm install x402-safe

Use

import { safeFetch } from "x402-safe";

// your existing x402 payment executor (x402-fetch, x402-axios, your own)
const pay = (paymentRequirements) => x402Pay(url, paymentRequirements);

const res = await safeFetch(url, {}, {
  pay,
  policy: "block-ghosts",            // block unverified recipients (default)
  onCheck: ({ payTo, trust, decision }) =>
    console.log(`${payTo}: ${trust.verdict} -> ${decision.allow ? "pay" : "BLOCKED"}`),
});

If the recipient is a ghost/sybil, safeFetch throws X402_SAFE_BLOCKED instead of paying.

Policies

• block-ghosts (default) — pay only verified, settlement-backed recipients; block unverified.
• block-unknown — also block when AgentRank can't be reached.
• warn — pay anyway, but surface the verdict via onCheck.
• allow — never block (telemetry only).

Just the check

import { checkAgentTrust } from "x402-safe";

const t = await checkAgentTrust("blockrun.ai");   // wallet or domain
// { verified: true, score: 870, settlement: { usd: 1026, payers: 37, substrate: "x402" }, verdict: "..." }

How the verdict works

AgentRank ranks agents by real on-chain settlement weighted by payer reputation (PageRank on the USDC payment graph, de-noised, sybil-tested). A recipient is verified only if it has actually settled value that traces back to reputable payers. Sybils and ghosts score ~0 because you cannot fake real settlement. Method: https://github.com/andysalvo/agentrank.

Also available

• MCP tool — the same check as check_agent_trust over MCP: https://api.agentrank.info/mcp.
• Badge — https://api.agentrank.info/badge/{wallet|domain}.svg.

MIT. Built by Crest Deployment Systems LLC.