LiveFreeOpen source (MIT)

Check every payment before your agent signs it

Guard compares each payment request with what we measured for that seller, then warns or blocks by your rules.

Add Guard (free)Try the sandbox

What it checks

Payout address seen before
Price above what we last measured
Our last check is recent
Request names the host you called

Runs inside your agent. Only the seller’s host name reaches us.

Try it

Example facts for seller.example. No wallet, nothing is paid. Example

The seller asks for

The same payout and price A new payout address Twice the price

Your rule

Warn only (default)Block a new payout Block both

Allowed with 1 warning

The price is above what we last measured on this route. The payment goes ahead; the warning reaches your logs.

Reason code: price_above_observed (warn) · Guard: createPrePaymentGuard()

FreeOpen source. Optional paid check for big payments: $0.001 after 25 free a day.All prices

For developers

Install (npm + PyPI 0.2.1)

npm install @botsrated/x402-preflight
pip install botsrated

@x402/fetch

import { x402Client, wrapFetchWithPayment } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { createPrePaymentGuard } from "@botsrated/x402-preflight";

const client = new x402Client();
registerExactEvmScheme(client, { signer });
const guard = createPrePaymentGuard();                      // default: warns, never blocks on payTo
client.onBeforePaymentCreation(guard.beforePaymentCreation);
const paidFetch = guard.wrapFetch(wrapFetchWithPayment(fetch, client));   // tells the guard which URL is paid

@x402/mcp (paid MCP tool calls)

import { createx402MCPClient } from "@x402/mcp";
import { createPrePaymentGuard, mcpPaymentApprover } from "@botsrated/x402-preflight";

const guard = createPrePaymentGuard();
const mcp = createx402MCPClient({ /* ... */
  onPaymentRequested: mcpPaymentApprover(guard, "https://seller.example/mcp") });

Python

from botsrated import STRICT_GUARD_POLICY, PrePaymentGuard

guard = PrePaymentGuard(policy=STRICT_GUARD_POLICY)    # the policy is your choice
client.on_before_payment_creation(guard.x402_hook)     # x402 Python client
get = guard.wrap_get(x402_requests(client).get)        # tells the guard which URL is paid

Agent frameworks

Every stack	LangChain, OpenAI Agents SDK, LangGraph, CrewAI, Vercel AI SDK, Mastra and more, three steps each. Every stack →
Any MCP client	`https://botsrated.com/mcp` (free tool `preflight`)

Source and README: npm, PyPI. Reference: /docs.

Every reason code

Reason `code`	When	Default	`strictGuardPolicy`
`payto_not_observed`	The payTo is not among the payTos our probes recorded for the host (same network).	warn	block
`payto_invalid`	The payTo is not a 20-byte hex address.	warn	block
`price_above_observed`	Same route, amount above the last amount we recorded.	warn	warn
`resource_url_mismatch`	The 402's resource.url names another host than the URL being paid (when the guard knows that URL).	block	block
`no_request_url`	The URL being paid is unknown (no guard.wrapFetch / forRequest).	off	block
`data_stale`	Our latest probe of the host is older than 24 hours.	info	info
`not_covered`	We have no probe record for the host. Says nothing about the seller.	info	info
`low_valid_402_rate`	Recent valid-402 rate below your minValid402Rate (only when you set one, 3+ recent probes).	off	off

Fail-open by default

If BotsRated is unreachable or the guard errors, the payment goes ahead (failOpen: true). resource_url_mismatch still blocks. Stricter setup:

import { createPrePaymentGuard, strictGuardPolicy } from "@botsrated/x402-preflight";

const guard = createPrePaymentGuard({
  policy: { ...strictGuardPolicy, priceAboveObserved: "block", minValid402Rate: 0.8 },
  failOpen: false,                 // stop the payment if BotsRated can't be reached
  paidCheckAtOrAboveUsd: 0.25,     // paid check ($0.001 after the free daily ones) for bigger payments
  onDecision: (d) => console.log(d.action, d.reasons),
});

Sandbox JSON

Quote in the 402

{
  "scheme": "exact",
  "network": "eip155:8453",
  "amount": "2000",
  "payTo": "0x1111111111111111111111111111111111111111",
  "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
}

Decision

{
  "action": "allow",
  "host": "seller.example",
  "reasons": [
    {
      "code": "price_above_observed",
      "detail": "the quoted amount (2000 atomic units) is above the last amount BotsRated recorded on this route (1000).",
      "effect": "warn"
    }
  ],
  "facts": {
    "covered": true,
    "host": "seller.example",
    "knownPayTos": [
      "0x1111111111111111111111111111111111111111"
    ],
    "observedNetwork": "eip155:8453",
    "probedUrl": "https://seller.example/api/search",
    "observedAmount": "1000",
    "stale": false,
    "receiptUrl": "https://botsrated.com/receipt/example-receipt-id",
    "source": "preflight"
  },
  "disputeUrl": "https://botsrated.com/disputes"
}

Questions

Can Guard move money?

No. It only advises your own x402 client. It can’t sign or send a payment.

What does BotsRated see?

Only the seller’s host name. Never the path, wallet, amount or payment header.

Is a block a judgment of the seller?

No. It applies your rule to what we measured, with a link to the receipt.

What if BotsRated is down?

By default the payment goes ahead (fail-open). You can switch that off.