Webhooks allow you to react to important events in your project by sending HTTP POST requests to a URL you specify.

For example, you can use webhooks to:

  • Update your CRM when a user signs up for your project.
  • Notify your team in Slack when a new user subscribes to a paid plan.
  • Keep your database in sync when a user is created or updated.
  • Get noticed when a user reached their quota limit.

Webhooks examples

Register a webhook

To register a webhook:

  • Open the Webhooks page in your dashboard.
  • Then click on create a webhook
  • Enter the URL of the endpoint that will receive the webhook requests.
  • Enter a description for you to remember what this webhook is for.
  • Select all the events you want to receive HTTP requests for.
You can register as many webhook URLs as you want. Every webhook URL can handle one or more subscription.

Webhooks examples

Security considerations

Every webhook request sent by Kobble will be signed with a secret key.

It’s crucial to validate the signature of the request to ensure that it was sent by Kobble and not by a malicious user.

To validate the signature, you need to compare the signature sent in the Kobble-Signature header with the signature of the request body.

The signature is a HMAC-SHA256 hash of the request body using the secret key as the key.

Get your secret key

You can get your secret key in the webhook detail page.

Webhook detail

Validate the signature

To validate the signature, you need to compare the signature sent in the Kobble-Signature header with the signature of the request body.

Here is an example of how to validate the signature in Node.js and Python:

import { createHmac } from 'crypto';

const isValidSignature = (
receivedBody: string,
receivedSignature: string,
secret: string): boolean =>
    const secretBuffer = Buffer.from(secret, 'hex');
    const generatedSignature = createHmac('sha256', secretBuffer)

    return receivedSignature === generatedSignature;
The Node.js SDK or Go SDK provides a method to validate the signature for you.

Request Headers

Kobble will always send the following headers with a webhook request:

  • Kobble-Signature: ‘signature’,
  • Kobble-Signature-Algorithm: sha256 by default
  • User-Agent: Kobble Webhooks/1.0

Test a webhook

The easiest way to test a webhook is to use the Send ping event button located in the webhook detail page.

Webhooks ping

Then, you can check the result on the latest deliveries section.

Webhooks deliveries

If you want to test a webhook with a specific payload, the best way is to use the application as a user would do.

Retry policy

Kobble will retry sending the webhook request up to 5 times if the server responds with a 5xx status code or if the request times out.

The retry policy is exponential, starting with a delay of 10 seconds and doubling the delay for each retry.

If the webhook request fails after 5 retries, Kobble will stop sending the request and mark the webhook as failed.

Delivery behavior

Kobble will send the webhook request as soon as possible after the event occurs.

The delivery behavior is defined as “at least once”, meaning that Kobble will try to deliver the webhook request at least once.

In rare cases, the webhook request may be delivered more than once due to network issues or race conditions.

To handle this, you should make your webhook endpoint idempotent, meaning that it should be safe to call the endpoint multiple times with the same data.