August 3, 2026

mppx now supports relays. A relay is a networked interface that abstracts payment-method settlement away from your application, reducing integration complexity and giving you new capabilities.

What a relay does

A relay sits between your application and the payment settlement layer. It handles two lifecycle operations:

• Validation checks whether a payment Credential is valid and can be accepted by the underlying payment rail.
• broadcast revalidates the payment Credential, finalizes or accepts payment, and returns the information needed to create a Receipt.

Relays give applications one interface for payment finalization while relay operators handle the details of each payment method.

Add a relay

Tempo charges

Pass a Tempo API key to tempo.charge. Your mppx integration automatically uses the Tempo relay.

import { Mppx, tempo } from 'mppx/server'
 
const mppx = Mppx.create({
  methods: [
    tempo.charge({
      relay: {
        apiKey: process.env.TEMPO_API_KEY!,
      },
    }),
  ],
})

You can point the same integration at a Tempo API-compatible service with relay.apiBaseUrl.

Other payment methods

For any other payment method, connect your relay to the validate and broadcast hooks with Method.toServer:

import { Method } from 'mppx'
import { charge } from './method'
 
export const chargeServer = Method.toServer(charge, {
  async broadcast({ credential, request }) { 
    return relay.broadcast({ credential, request })
  },
  async validate({ credential, request }) { 
    return relay.validate({ credential, request })
  },
})

Author a relay

MPP does not require relays or require them to conform to a single interface. Relay authors can define their own API shape, payment method support, and underlying functionality—as long as they preserve the core MPP control flow.

Learn more

• Relay integration guide