How do I test a webhook endpoint locally?

A few common ways:

1) Run your server locally

Start your webhook handler on a local port, e.g. http://localhost:3000/webhook.

2) Send a test request with curl or Postman

Example:

curl -X POST http://localhost:3000/webhook \
  -H "Content-Type: application/json" \
  -d '{"event":"test","id":"123"}'

This is the simplest way to verify:

• your endpoint accepts the right method
• it parses the body correctly
• signature/auth validation works
• your handler returns the expected response

3) Expose your local server to the internet

If the webhook provider needs a public URL, use a tunneling tool like:

• ngrok
• Cloudflare Tunnel
• localtunnel

Example with ngrok:

ngrok http 3000

It gives you a public URL like:

https://abc123.ngrok.io/webhook

Point the webhook provider to that URL.

4) Replay real webhook payloads

If the provider supports it, use:

• their dashboard’s “send test event” feature
• CLI tools
• saved payloads from production logs

5) Log the raw request

When testing locally, log:

• headers
• raw body
• query params
• request method

This helps a lot with signature verification issues, because many providers require the exact raw body.

6) Use a mock webhook sender

You can simulate a webhook by writing a small script that POSTs to your endpoint.

Example Node.js:

import fetch from "node-fetch";

await fetch("http://localhost:3000/webhook", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ event: "payment.succeeded", id: "evt_123" })
});

Common gotchas

• Webhooks usually require POST
• Some providers require the raw body, not parsed JSON
• Your endpoint may need to respond quickly with 2xx
• If testing through a tunnel, the URL can change when you restart the tunnel
• Make sure your local firewall isn’t blocking the port

If you want, I can show you how to test a webhook locally in Node.js, Python, or Go, including signature verification.