Underscoredone

Underscoredone is an x402-native service at https://mortgage-amortization.underscoredone.com, 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. 1 endpoint listed.

Base

Offers

Offer	Endpoint	Price
Calculate Give this API a loan amount, an interest rate, and a repayment term, and it returns the exact monthly payment plus a full month-by-month schedule: interest paid, principal repaid, and balance remaining for every payment. Ask what an extra $300 a month, or a $10,000 lump sum in month 24, would do and it reports the months and interest saved. Every figure uses banker's rounding at pinned precision,	`/m/bz-mortgage-amortization-underscoredone-com/calculate`	0.01 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-mortgage-amortization-underscoredone-com/calculate')
// 402 challenge signed and settled automatically; response includes Payment-Receipt

Or inspect the challenge yourself:

curl -i https://api.meshgateway.co/m/bz-mortgage-amortization-underscoredone-com/calculate
# HTTP/1.1 402 Payment Required
# WWW-Authenticate: Payment id="…", method="evm", intent="charge", …