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This guide walks you through using ngrok to receive PagerDuty webhooks on your localhost app. By integrating ngrok with PagerDuty, you can:
  • Develop and test PagerDuty webhooks locally without deploying to a public environment or setting up HTTPS.
  • Inspect and troubleshoot requests from PagerDuty in real time via the inspection UI and API.
  • Modify and replay PagerDuty webhook requests with a single click instead of reproducing events manually in your PagerDuty account.
  • Secure your app with PagerDuty 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 PagerDuty.

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3. Configure PagerDuty to send webhooks

PagerDuty can send webhook requests to your app when events occur in your account. To register for those events:
  • Sign in to PagerDuty.
  • Click Integrations and then Generic Webhooks.
  • On Your Webhooks, click + New Webhook for your application.
  • On New Webhook, enter your ngrok URL in WEBHOOK URL (for example, https://1a2b-3c4d-5e6f-7g8h-9i0j.ngrok.app).
  • Select Service as SCOPE TYPE, select a service for SCOPE, click Select all under EVENT SUBSCRIPTION, and click Add Webhook.
  • In the Webhook subscription created popup, click Copy to copy the webhook payload signing secret for verification, then click OK.
  • Click your new webhook, scroll to Test, click Send Test Event, and Yes, Send Event.
Confirm your localhost app receives the test event and logs both headers and body in the terminal.

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Run webhooks with PagerDuty and ngrok

PagerDuty sends different request body contents depending on the event. To trigger new calls from PagerDuty to your app:
  • Go to Services and Service Directory, then + New Service.
  • Create a service (click Next until Integrations, then Create service without an integration).
  • On the service page, click New Incident, select your service, enter a title, set Urgency to Low, and click Create Incident.
Confirm your localhost app receives the incident event 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 PagerDuty 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:
  • Create a Traffic Policy file named pagerduty_policy.yml. Replace {your webhook payload signing} with the value you copied when creating the webhook: 
    on_http_request:
  - actions:
      - type: verify-webhook
        config:
          provider: pagerduty
          secret: "{your webhook payload signing}"
  • Restart ngrok with the policy file: 
    ngrok http 3000 --traffic-policy-file pagerduty_policy.yml
  • Create a new incident in PagerDuty to trigger the webhook.
Your app should receive the request and log it in the terminal.