Vercel Webhooks & Events

Overview

Handle Vercel webhook events (deployment.created, deployment.ready, deployment.error) with HMAC signature verification. Covers both integration webhooks (Vercel Marketplace) and project-level deploy hooks.

Prerequisites

• HTTPS endpoint accessible from the internet
• Webhook secret from Vercel dashboard or integration settings
• crypto module for HMAC signature verification

Instructions

Step 1: Register a Webhook

In the Vercel dashboard:

1. Go to Settings > Webhooks
2. Add your endpoint URL (must be HTTPS)
3. Select events to subscribe to
4. Copy the webhook secret for signature verification

Or for Integration webhooks, configure in the Integration Console at vercel.com/dashboard/integrations.

Step 2: Verify Webhook Signature

// api/webhooks/vercel.ts
import type { VercelRequest, VercelResponse } from '@vercel/node';
import crypto from 'crypto';

const WEBHOOK_SECRET = process.env.VERCEL_WEBHOOK_SECRET!;

function verifySignature(body: string, signature: string): boolean {
  const expectedSignature = crypto
    .createHmac('sha1', WEBHOOK_SECRET)
    .update(body)
    .digest('hex');
  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expectedSignature)
  );
}

export default async function handler(req: VercelRequest, res: VercelResponse) {
  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' });
  }

  // Get raw body for signature verification
  const rawBody = JSON.stringify(req.body);
  const signature = req.headers['x-vercel-signature'] as string;

  if (!signature || !verifySignature(rawBody, signature)) {
    return res.status(401).json({ error: 'Invalid signature' });
  }

  // Process the event
  const event = req.body;
  await handleEvent(event);

  res.status(200).json({ received: true });
}

Step 3: Handle Deployment Events

// lib/webhook-handlers.ts
interface VercelWebhookEvent {
  id: string;
  type: string;
  createdAt: number;
  payload: {
    deployment: {
      id: string;
      name: string;
      url: string;
      meta: Record<string, string>;
    };
    project: {
      id: string;
      name: string;
    };
    target: 'production' | 'preview' | null;
    user: { id: string; email: string; username: string };
  };
}

async function handleEvent(event: VercelWebhookEvent): Promise<void> {
  switch (event.type) {
    case 'deployment.created':
      console.log(`Deployment started: ${event.payload.deployment.url}`);
      // Notify Slack, update status board, etc.
      break;

    case 'deployment.ready':
      console.log(`Deployment ready: ${event.payload.deployment.url}`);
      // Run smoke tests against the deployment URL
      // Notify team of successful deploy
      if (event.payload.target === 'production') {
        await notifyProductionDeploy(event);
      }
      break;

    case 'deployment.error':
      console.error(`Deployment failed: ${event.payload.deployment.id}`);
      // Alert on-call engineer
      // Create incident ticket
      await notifyDeploymentError(event);
      break;

    case 'deployment.canceled':
      console.log(`Deployment canceled: ${event.payload.deployment.id}`);
      break;

    case 'project.created':
      console.log(`New project: ${event.payload.project.name}`);
      break;

    case 'project.removed':
      console.log(`Project removed: ${event.payload.project.name}`);
      break;

    default:
      console.log(`Unhandled event type: ${event.type}`);
  }
}

Step 4: Idempotency — Prevent Duplicate Processing

// lib/idempotency.ts
// Vercel may retry webhook delivery — track processed event IDs
const processedEvents = new Set<string>(); // Use Redis in production

async function processWebhookIdempotent(
  event: VercelWebhookEvent,
  handler: (e: VercelWebhookEvent) => Promise<void>
): Promise<boolean> {
  if (processedEvents.has(event.id)) {
    console.log(`Skipping duplicate event: ${event.id}`);
    return false;
  }

  await handler(event);
  processedEvents.add(event.id);
  return true;
}

Step 5: Slack Notification Example

// lib/notifications.ts
async function notifyProductionDeploy(event: VercelWebhookEvent): Promise<void> {
  const { deployment, project, user } = event.payload;

  await fetch(process.env.SLACK_WEBHOOK_URL!, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      text: `Production deploy complete`,
      blocks: [
        {
          type: 'section',
          text: {
            type: 'mrkdwn',
            text: [
              `*${project.name}* deployed to production`,
              `By: ${user.username}`,
              `URL: https://${deployment.url}`,
              `Commit: ${deployment.meta?.githubCommitMessage ?? 'N/A'}`,
            ].join('\n'),
          },
        },
      ],
    }),
  });
}

async function notifyDeploymentError(event: VercelWebhookEvent): Promise<void> {
  await fetch(process.env.SLACK_WEBHOOK_URL!, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      text: `Deployment FAILED for ${event.payload.project.name} — ${event.payload.deployment.id}`,
    }),
  });
}

Step 6: Test Webhooks Locally

# Use the Vercel CLI to test webhook signatures
# Or use a tunnel service for local testing
npx localtunnel --port 3000
# Gives you a public URL like https://xxx.loca.lt

# Send a test webhook payload
curl -X POST http://localhost:3000/api/webhooks/vercel \
  -H "Content-Type: application/json" \
  -H "x-vercel-signature: $(echo -n '{"type":"deployment.ready","id":"test"}' | openssl dgst -sha1 -hmac 'your-secret' | awk '{print $2}')" \
  -d '{"type":"deployment.ready","id":"test"}'

Webhook Event Types

Output

• Webhook endpoint with HMAC signature verification
• Event handlers for deployment lifecycle events
• Idempotent processing preventing duplicates
• Slack notifications for production deploys and failures

Error Handling

Examples

Process a deployment webhook exactly once

Verify the raw-body HMAC signature before parsing the event, reject absent or invalid signatures with a generic response, and persist the event ID in an idempotency store before any side effect. Acknowledge quickly and hand longer work to a controlled background queue. Test duplicate delivery and an invalid signature with synthetic events in preview, and keep notification payloads free of tokens, environment values, and customer request data.

Resources

• Vercel Webhooks API
• Setting Up Webhooks
• Deploy Hooks
• Integration Webhooks

Next Steps

For performance optimization, see vercel-performance-tuning.