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

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3. Configure Linear to send webhooks

Linear can send webhook requests to your app when events occur in your workspace. To register for those events:
  • Sign in to Linear with an account that has administrative privileges.
  • Click your profile icon and then Settings.
  • Go to Administration and API.
  • In Webhooks, click Create Webhook.
  • Enter a name in Name (for example, ngrok Integration Webhook) and your ngrok URL in URL (for example, https://1234-abcd-5e6f-7g8h-9i0j.ngrok.app).
  • Copy and store the Signing secret.
  • Under Data change events, choose the events that should trigger the webhook.
  • Click Create.

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Run webhooks with Linear and ngrok

Linear sends a POST request to your app through ngrok when the selected events occur. To trigger a webhook event:
  • In your Linear workspace, create a new issue or update an existing issue in a project.
Confirm your localhost app receives the webhook and logs both headers and body in the terminal.
Different messages are sent depending on the trigger events you chose.
To review deliveries in Linear, go to Settings, Administration, API, Webhooks, and select your webhook.

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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 Linear 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 your Linear webhook settings, copy the Secret value (Linear generates it when you create the webhook).
  • Create a Traffic Policy file named linear_policy.yml. Replace {your secret} with the value you copied: 
    on_http_request:
  - actions:
      - type: verify-webhook
        config:
          provider: linear
          secret: "{your secret}"
  • Restart ngrok with the policy file: 
    ngrok http 3000 --traffic-policy-file linear_policy.yml
  • Create or update an issue in Linear to trigger the webhook.
Your app should receive the request and log it in the terminal.