MPPFrontier

Install the required dependencies:

npm install mppx stripe

Create an endpoint that checks for a 0.50 USD payment on each request and returns an HTTP 402 challenge if no payment is present. If it verifies a payment, it returns a receipt.

import crypto from 'crypto';
import StripeClient from 'stripe';
import { Mppx, stripe } from 'mppx/server';

// Secret used to secure payment challenges
// https://mpp.dev/protocol/challenges#challenge-binding
const mppSecretKey = crypto.createHmac("sha256", process.env.STRIPE_SECRET_KEY!).update("mpp-challenge-signing").digest("base64");

const stripeClient = new StripeClient(process.env.STRIPE_SECRET_KEY!);

const stripeMachinePayments = stripe.create({
  client: stripeClient,
  networkId: process.env.STRIPE_PROFILE_ID!,
  livemode: !process.env.STRIPE_SECRET_KEY!.includes('_test_')
});

const mppx = Mppx.create({
  methods: [stripeMachinePayments.spt.charge()],
  secretKey: mppSecretKey,
});

export async function handler(request: Request) {
  const response = await mppx.compose([
    'stripe/charge',
    { amount: '0.50', currency: 'usd', decimals: 2 },
  ])(request);

  if (response.status === 402) return response.challenge;

  return response.withReceipt(Response.json({ data: '...' }));
}

Use MPP to accept payments from agents with a variety of payment methods, including cards through Shared Payment Tokens (SPTs) and stablecoin payments.

See availability requirements for SPTs and stablecoin payments to learn more.

By default, the endpoint you create supports SPTs. Make sure that you also add support for stablecoin payments to support agents with crypto wallets and charge for payments as low as 0.01 USDC.

To accept stablecoin payments, follow the steps below to:

1. Create a deposit address
2. Update your endpoint

Create a deposit address

Agents with stablecoins send payments to this onchain address on supported blockchains, such as Tempo. Stripe automatically offramps these payments and settles them into your Stripe balance.

curl https://api.stripe.com/v1/crypto/deposit_addresses \
  -u "$STRIPE_SECRET_KEY:" \
  -H "Stripe-Version: 2026-05-27.preview" \
  -d network=tempo

Create a deposit address and store the returned address as TEMPO_DEPOSIT_ADDRESS in your servers environment variables.

You can create deposit addresses as often as you want, but we recommend that you keep these calls off your core request path.

Update your endpoint

Add the deposit address to your stripeMachinePayments configuration, then rebuild mppx with defaultMethods(), which includes SPTs and stablecoin payments. Update compose to accept payments with either method.

const stripeMachinePayments = stripe.create({
  client: stripeClient,
  networkId: process.env.STRIPE_PROFILE_ID!,
  livemode: !process.env.STRIPE_SECRET_KEY!.includes('_test_'),
  depositAddresses: {
    tempo: process.env.TEMPO_DEPOSIT_ADDRESS!
  },
});

const mppx = Mppx.create({
  methods: stripeMachinePayments.defaultMethods(),
  secretKey: mppSecretKey,
});

export async function handler(request: Request) {
  const response = await mppx.compose(
    ['tempo/charge', { amount: '0.50' }],
    ['stripe/charge', { amount: '0.50', currency: 'usd', decimals: 2 }],
  )(request);

  if (response.status === 402) return response.challenge;

  return response.withReceipt(Response.json({ data: '...' }));
}

Test with mppx validate

Run mppx validate to automatically verify your implementation end-to-end. The command tests discovery, challenge formats, error handling, and the full payment flow.

npx mppx@latest validate http://localhost:4242

We recommend running validate against both a sandbox and live mode version of your server. In a sandbox, the CLI automatically completes roundtrip test transactions against your server. In live mode, the CLI can also complete roundtrip transactions with real funds.

Test manually

You can also test each step individually. First, verify your server returns a 402 with the payment requirements:

curl -fsSL https://tempo.xyz/install | bash
tempo wallet login
tempo wallet fund
tempo request -X POST --json '{}' http://localhost:4242/paid

Test with a Stripe sandbox

To test in a sandbox:

1. Configure your server to use your sandbox Stripe API key.
2. Create a Stripe profile for your sandbox and use the profile_test_ ID.
3. Create a Tempo deposit address in your sandbox account:

curl https://api.stripe.com/v1/crypto/deposit_addresses \
  -u "$STRIPE_SECRET_KEY:" \
  -H "Stripe-Version: 2026-05-27.preview" \
  -d network=tempo

Store the returned address as your TEMPO_DEPOSIT_ADDRESS environment variable. The configuration above detects your sandbox API key and sets livemode to false. mppxs stripe.create automatically configures Tempo testnet.