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This guide shows you how to use ngrok to receive Worldline webhooks on your localhost app. By integrating ngrok with Worldline, you can:
  • Develop and test Worldline webhooks locally without deploying to a public environment or setting up HTTPS.
  • Inspect and troubleshoot requests from Worldline in real time via the inspection UI and API.
  • Modify and replay Worldline webhook requests with a single click instead of reproducing events manually in your Worldline account.
  • Secure your app with Worldline webhook validation provided by ngrok. Invalid requests are blocked by ngrok before reaching your app.

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What you’ll need

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1. Start your app

For this tutorial, you can use the sample Node.js app on GitHub. To install the sample, run the following in a terminal: 
git clone https://github.com/ngrok/ngrok-webhook-nodejs-sample.git
cd ngrok-webhook-nodejs-sample
npm install
Then start the app: 
npm start
The app runs on port 3000 by default. You can confirm it’s running by visiting http://localhost:3000. The app logs request headers and body in the terminal and shows a message in the browser.

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2. Expose your app with ngrok

Once your app is running locally, you’re ready to put it online securely using ngrok.
The ngrok agent uses your authtoken to authenticate when you start a tunnel.
  • Start ngrok: 
    ngrok http 3000
  • Copy the URL ngrok displays. Your app is now exposed at that URL for use with Worldline.

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3. Configure Worldline to send webhooks

Worldline can send webhook requests to your app when payment and other events occur. To register for those events:
  • Sign in to Worldline.
  • Go to Developer > Webhooks and click Create a Webhook.
  • Click Generate webhook keys and note the Secret Webhook Key.
  • Click Add webhook endpoint, enter your ngrok URL in Endpoint URL (for example, https://1a2b-3c4d-5e6f-7g8h-9i0j.ngrok.app), and click Confirm.

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Run webhooks with Worldline and ngrok

Worldline sends different request body contents depending on the event. To trigger a test:
  • In Worldline, go to Payment links > Generate link.
  • Enter Amount and Order reference and click Generate link.
  • On Share link, copy the payment link, open it in a new tab, select Bancontact (or another method), and click Cancel.
Confirm your localhost app receives the POST and logs both headers and body in the terminal.

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Inspecting requests

ngrok’s Traffic Inspector captures all requests made through your ngrok endpoint to your localhost app. Select any request to view detailed information about both the request and response.
To avoid exposing secrets, accounts only collect traffic metadata by default. You must enable full capture in the Observability section of your account settings to capture complete request and response data.
Use the traffic inspector to:
  • Validate webhook payloads and response data
  • Debug request headers, methods, and status codes
  • Troubleshoot integration issues without adding logging to your app

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Replaying requests

Test your webhook handling code without triggering new events from your service using the Traffic Inspector’s replay feature:
  1. Send a test webhook from your service to generate traffic in your Traffic Inspector.
  2. Select the request you want to replay in the traffic inspector.
  3. Choose your replay option:
    • Click Replay to send the exact same request again
    • Select Replay with modifications to edit the request before sending
  4. (Optional) Modify the request: Edit any part of the original request, such as changing field values in the request body.
  5. Send the request by clicking Replay.
Your local application will receive the replayed request and log the data to the terminal.

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Secure webhook requests

ngrok can verify that incoming requests are from your Worldline webhook so only that traffic reaches your app.
Webhook verification is limited to 500 validations per month on free accounts. If you need more, you can upgrade to Hobbyist or Pay-as-you-go. See TPU Pricing for details.
To add verification:
  • Use the Secret Webhook Key you noted when creating the webhook (see Configure Worldline to send webhooks).
  • Create a Traffic Policy file named worldline_policy.yml. Replace {your webhook secret} with that value: 
    on_http_request:
  - actions:
      - type: verify-webhook
        config:
          provider: worldline
          secret: "{your webhook secret}"
  • Restart ngrok with the policy file: 
    ngrok http 3000 --traffic-policy-file worldline_policy.yml
  • Create a new payment link, open it, and complete or cancel a payment to trigger the webhook.
Your app should receive the request and log it in the terminal.