Webhooks

Modem Pay’s webhooks notify your server about key events, such as customer creation, payment intent updates, and successful charges. To receive and securely process these notifications, follow the steps outlined here for setting up, validating, and handling webhooks.

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Setting Up Webhooks

1. Define Your Webhook Endpoint:
   Create a dedicated POST endpoint on your server to receive webhook events from Modem Pay. Ensure this endpoint is accessible over HTTPS to maintain security.

2. Listening for Events:
   Your endpoint will receive a variety of event notifications (e.g., customer.created, payment_intent.created, charge.succeeded). The event type is provided in the event field, while the main data is within the payload.

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Webhook Security and Signature Validation

To confirm the integrity of incoming events, Modem Pay includes a unique x-modem-signature header in each webhook request. This header allows you to verify that the event originated from Modem Pay.

1. Retrieve the Signature:
   In your webhook endpoint, extract the x-modem-signature header from the incoming request.

2. Use modempay.webhooks.composeEventDetails for Validation:
   Pass the payload, signature, and your unique Modem Pay secret to the modempay.webhooks.composeEventDetails function. This function performs the necessary checks, verifying the signature and parsing the payload.

// Example usage
const event = modempay.webhooks.composeEventDetails(
    payload,
    xSignatureHeader,
    modemSecret
);

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Modem Pay CLI

The Modem Pay CLI is a tool designed to simplify integration testing by offering features like authentication, webhook management, and event simulation only in a test environment.

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Installation

To install the Modem Pay CLI, run:

npm install -g modem-pay-cli  

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Commands

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1. Login

Authenticates a user and generates an access token, business ID, and account ID. Authentication is required to access other CLI features.

Usage:

$ modempay login 

✔ Enter your Modem Pay email: › mercury@modempay.com
✔ Enter your password: › *******
✅ Login successful! Credentials saved.

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2. Listen

The listen command creates a secure public tunnel using Localtunnel to forward webhooks to a local endpoint. This is particularly useful for testing webhooks during development.

Disclaimer:

• The CLI leverages Localtunnel to generate the public URL. In some cases, a public URL might not be provisioned successfully due to network issues.
• This feature should only be used in test environments.

Usage:

$ modempay listen --forward-url <local-endpoint>  

Options:

• --forward-url: Specifies your local endpoint to receive webhook events.

Example:

$ modempay listen --forward-url=http://localhost:3000/webhook  

Ready! Your webhook signing secret is '{{WEBHOOK_SIGNING_SECRET}}' (^C to quit)

This will create a public tunnel pointing to http://localhost:3000/webhook.

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3. Trigger

Simulates events for testing purposes.

Usage:

$ modempay trigger <event-type>  

Supported Event Types:

• Customer Events: "customer.created", "customer.updated", "customer.deleted"
• Payment Intent Events: "payment_intent.created", "payment_intent.cancelled"
• Charge Events: "charge.succeeded", "charge.cancelled", "charge.created", "charge.updated"

Example:

$ modempay trigger charge.succeeded 

🔧 Executing event: "charge.succeeded"
✅ Event "charge.succeeded" triggered successfully.

This sends a charge.succeeded event payload to the configured webhook endpoint for testing.

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Event Structure

Upon successful validation, modempay.webhooks.composeEventDetails returns an Event object containing the event type and payload data. The event types you may receive include:

• Customer Events: "customer.created", "customer.updated", "customer.deleted"
• Payment Intent Events: "payment_intent.created", "payment_intent.cancelled"
• Charge Events: "charge.succeeded", "charge.cancelled", "charge.created", "charge.updated"

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Example Usage

Here’s an example of using modempay.webhooks.composeEventDetails to handle incoming webhooks in a Node.js application:

const express = require("express");
const bodyParser = require("body-parser");
const ModemPay = require("modem-pay");

const modempay = new ModemPay();
const app = express();
app.use(bodyParser.json());

app.post("/webhook", (req, res) => {
  const payload = req.body;
  const signature = req.headers["x-modem-signature"];
  const secret = process.env.MODEM_WEBHOOK_SECRET;

  try {
    const event = modempay.webhooks.composeEventDetails(payload, signature, secret);
    // Process the event
    switch (event.event) {
      case "customer.created":
        // Handle new customer logic
        break;
      case "charge.succeeded":
        // Process successful payment
        break;
      // Add other cases as needed
    }

    res.status(200).send("Webhook processed!");
  } catch (error) {
    res.status(400).send("Invalid signature!");
  }
});

app.listen(3000, () => console.log("Listening for webhooks on port 3000"));

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Recommended Response

For each webhook event, respond to Modem Pay with an HTTP 200 OK status as confirmation. This ensures Modem Pay won’t re-send the event unless there’s an error response.

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Summary

By following these steps, you can securely receive and process webhook events from Modem Pay, automating actions based on customer interactions and payment flows. Make sure to store and securely handle the event data, as each event may carry critical transaction or customer information relevant to your application.