Webhooks

Introduction

Webhooks allow you to subscribe to changes in Certifier and receive real-time HTTP requests to a specified URL when those changes occur.

This mechanism is ideal for real-time data synchronization (e.g., ETL pipelines) and event-driven automation (e.g., Certifier's Zapier integration relies on webhooks).

Creating Webhooks

You can create, view, and manage your webhooks in the Certifier dashboard:

Settings → Developers → Webhooks

Webhook Payloads

Webhooks are sent as POST requests with a JSON payload. The payload structure depends on the event type.

Example Payload

{
  "id": "01jmyw7nvtk2372kwn572mwfq7",
  "type": "credential.created",
  "createdAt": "2025-02-25T15:39:59.680Z",
  "data": {
    "resource": {
      "id": "01jmyw4zyyrtyntqcevy2zmbnf",
      "type": "credential"
    }
  }
}

Webhook Security

To ensure authenticity, all webhook requests are signed using a cryptographic signature.

Signature Verification

Each webhook request includes an X-Webhook-Signature header, which contains a SHA256 HMAC signature of the request payload, signed with your webhook secret.

How to Verify Signatures

1. Retrieve the X-Webhook-Signature header.
2. Compute the HMAC SHA256 signature using your webhook secret and the request payload.
3. Compare your computed signature with the received signature using a timing-safe comparison.

Example in Node.js

const crypto = require("crypto");

/**
 * Verifies the authenticity of a webhook request using HMAC SHA256.
 * @param {string} payload - The raw webhook payload.
 * @param {string} receivedSignature - The received X-Webhook-Signature header.
 * @param {string} secret - Your webhook secret.
 * @returns {boolean} - Returns true if the signature is valid, false otherwise.
 */
function verifyWebhookSignature(payload, receivedSignature, secret) {
  if (!receivedSignature) {
    console.error("Missing webhook signature");
    return false;
  }

  try {
    const hmac = crypto.createHmac("sha256", secret);
    hmac.update(payload, "utf8");
    const expectedSignature = hmac.digest("hex");

    return crypto.timingSafeEqual(Buffer.from(receivedSignature, "hex"), Buffer.from(expectedSignature, "hex"));
  } catch (error) {
    console.error("Error verifying webhook signature:", error);
    return false;
  }
}

// Usage example
const webhookPayload = JSON.stringify(request.body);
const receivedSignature = request.headers["x-webhook-signature"];
const webhookSecret = "your_webhook_secret";

if (!verifyWebhookSignature(webhookPayload, receivedSignature, webhookSecret)) {
  throw new Error("Invalid webhook signature");
}

Webhook Event Types

Webhooks follow a resource.action naming pattern. The available events are:

Best Practices

• Verify webhook signatures to ensure authenticity.
• Use HTTPS endpoints for security.
• Respond within 5 seconds to avoid timeouts.
• Process webhooks asynchronously to improve reliability.
• Log webhook deliveries and failures for debugging purposes.
• Use idempotency mechanisms to handle duplicate webhook deliveries.

Retry Mechanism

If your server fails to respond with a 2xx HTTP status code, we will retry the delivery using an exponential backoff schedule:

1. 3 minutes after the first failure
2. 6 minutes after the previous retry
3. 30 minutes after the previous retry
4. 1 hour after the previous retry
5. 12 hours after the previous retry
6. 24 hours after the previous retry
7. 48 hours after the previous retry

Retry Headers

• X-Retry-Count: Indicates the retry attempt number (starts at 1). The initial attempt does not include this header.

Webhook Technical Details

Testing Webhooks

We recommend using webhook.site or RequestBin to inspect webhook payloads during development.

Monitoring & Debugging

You can track webhook deliveries, failures, and retries in the Certifier dashboard:

Settings → Developers → Webhooks → Events

Rate Limiting

Currently, there are no rate limits on webhook deliveries. However, we recommend implementing queue-based processing on your end to handle high event volumes efficiently.

Support

If you need assistance with webhooks, contact our support team or join the discussion on Discussions.