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:

Go to Settings > Webhooks
Add your endpoint URL (must be HTTPS)
Select events to subscribe to
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

Event	Trigger
`deployment.created`	New deployment started building
`deployment.ready`	Deployment build completed successfully
`deployment.error`	Deployment build failed
`deployment.canceled`	Deployment was canceled
`project.created`	New project created
`project.removed`	Project deleted
`domain.created`	Domain added to project
`integration.configuration.removed`	Integration uninstalled

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

Error	Cause	Solution
`401 Invalid signature`	Wrong webhook secret or body mismatch	Verify secret matches dashboard, use raw body for HMAC
Webhook not received	Endpoint not publicly accessible	Ensure HTTPS, check firewall rules
Duplicate processing	Webhook retried by Vercel	Implement idempotency with event ID tracking
`504 timeout` on webhook endpoint	Handler takes too long	Return 200 immediately, process async in background
Missing `x-vercel-signature`	Not a real Vercel webhook	Reject requests without the signature header

Resources

Next Steps

For performance optimization, see vercel-performance-tuning.

vercel-webhooks-events

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