Attester

Attester is an x402-native service at https://attester.dev, indexed from the x402 Bazaar (Coinbase's public discovery directory). It charges callers itself in USDC on Base and is paid directly at its own wallet; Monex Protocol passes your request and payment headers through untouched. 4 endpoints listed.

Base

Offers

Offer	Endpoint	Price
Judge QA Judge: grade an agent output against your rubric (structure, citations, claim support, length constraints) and receive a 0-100 score with a signed attestation. $0.10 USDC per grading.	`/m/bz-attester-dev/judge`	0.1 USDC
Spend Check Spend Check: should you pay this counterparty? Watchtower track record, CDP merchant catalog, and address hygiene combined into a clear/caution/avoid verdict with a signed attestation. $0.005 USDC per check.	`/m/bz-attester-dev/spend-check`	0.005 USDC
Package Exists Deterministic package existence for PyPI and npm, built from real published artifacts (never LLM guesses). Negative answers and typosquat-adjacency flags carry signed proof. $0.002 USDC per check.	`/m/bz-attester-dev/v1/package/exists`	0.002 USDC
Mcp Report Signed drift history for one MCP server: pins over time, every detected drift event, and a current verdict (stable, changed, or poisoning-suspect). $0.05 USDC per report.	`/m/bz-attester-dev/v2/mcp/report`	0.05 USDC

Machine-readable: openapi.json with x-payment-info offers.

Try it live

Run the full MPP flow from your browser: catch the 402, sign the payment with your wallet, and watch it settle on-chain.

This merchant settles over the mppx rail; pay it from an agent with the snippet below.

Pay with an agent

Any MPP or x402-compatible client works. With mppx, payment is automatic:

import { Mppx, evm } from 'mppx/client'
import { privateKeyToAccount } from 'viem/accounts'

const mppx = Mppx.create({
  methods: [evm({
    account: privateKeyToAccount(process.env.KEY),
    currencies: [evm.assets.base.USDC],
  })],
})

const res = await mppx.fetch('https://api.meshgateway.co/m/bz-attester-dev/judge')
// 402 challenge signed and settled automatically; response includes Payment-Receipt

Or inspect the challenge yourself:

curl -i https://api.meshgateway.co/m/bz-attester-dev/judge
# HTTP/1.1 402 Payment Required
# WWW-Authenticate: Payment id="…", method="evm", intent="charge", …