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

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3. Configure Calendly to send webhooks

Calendly can send webhook requests to your app when events occur in your account. To register for those events:
  • Sign in to Calendly.
  • On the My Calendly page, click Integrations in the top menu.
  • On the All integrations page, click the API and webhooks tile and then click Get a token under the Personal access tokens section.
  • On the Before you begin popup, click Continue, enter a name for the token in the Choose a name for this token field, click Create token, click Copy token, and then click Close.
  • On the Your personal access tokens page, scroll down and click Copy Key in the API Key section.
  • Open a terminal and run the following to get your account info: 
    curl --request GET --url https://api.calendly.com/users/me \
--header 'authorization: Bearer TOKEN'
    Replace TOKEN with the token value you copied.
  • Copy the value of the current_organization field and the uri field from the response.
  • Run the following to register the webhook: 
    curl --request POST --url https://api.calendly.com/webhook_subscriptions \
--header 'Authorization: Bearer TOKEN' \
--header 'Content-Type: application/json' --data '{
"url": "URL",
"events": [
    "invitee.created",
    "invitee.canceled"
],
"organization": "ORGANIZATION_URL",
"user": "USER_URL",
"scope": "user",
"signing_key": "KEY"
}'
    Replace URL with your ngrok URL (for example, https://1a2b-3c4d-5e6f-7g8h-9i0j.ngrok.app), TOKEN with the Calendly token, ORGANIZATION_URL with the current_organization value, USER_URL with the uri value, and KEY with the key you copied.
  • Confirm the response contains a resource attribute with the information you provided.

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Run webhooks with Calendly and ngrok

Calendly sends different request body contents depending on the event. To trigger new calls from Calendly to your app:
  • Use your Calendly link to schedule a meeting (for example, click 30 Minutes Meeting, select a date, and click Confirm).
If you don’t know your Calendly link, go to Calendly, click Account in the top right, click Share Your Link, and copy your link.
  • On the Enter Details page, enter your name and email and click Schedule Event.
Confirm your localhost app receives the invitee.created 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 Calendly 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:
  • In Calendly, go to Integrations, API and webhooks, and copy the API Key value (the same value you used to register your webhook).
  • Create a Traffic Policy file named calendly_policy.yml. Replace {your key} with the value you copied: 
    on_http_request:
  - actions:
      - type: verify-webhook
        config:
          provider: calendly
          secret: "{your key}"
  • Restart ngrok with the policy file: 
    ngrok http 3000 --traffic-policy-file calendly_policy.yml
  • Schedule a meeting from your Calendly link to trigger the webhook.
Your app should receive the request and log it in the terminal.