Vercel

The frontend cloud platform for deploying web applications.

Quick Start

Install CLI:

npm i -g vercel

Deploy:

vercel

Deploy to production:

vercel --prod

Project Setup

Connect Git Repository

1. Go to vercel.com/new
2. Import repository from GitHub/GitLab/Bitbucket
3. Configure build settings (auto-detected for most frameworks)
4. Deploy

vercel.json Configuration

{
  "buildCommand": "npm run build",
  "outputDirectory": "dist",
  "installCommand": "npm install",
  "framework": "nextjs",
  "regions": ["iad1"],
  "functions": {
    "api/**/*.ts": {
      "memory": 1024,
      "maxDuration": 10
    }
  },
  "rewrites": [
    { "source": "/api/:path*", "destination": "/api/:path*" }
  ],
  "redirects": [
    { "source": "/old", "destination": "/new", "permanent": true }
  ],
  "headers": [
    {
      "source": "/(.*)",
      "headers": [
        { "key": "X-Frame-Options", "value": "DENY" }
      ]
    }
  ]
}

Environment Variables

Setting Variables

Via Dashboard:

1. Project Settings > Environment Variables
2. Add key-value pairs
3. Select environments (Production, Preview, Development)

Via CLI:

vercel env add MY_VAR
vercel env ls
vercel env pull .env.local

Environment Types

// Production only
NEXT_PUBLIC_API_URL=https://api.example.com

// Preview (PR deployments)
NEXT_PUBLIC_API_URL=https://staging-api.example.com

// Development
NEXT_PUBLIC_API_URL=http://localhost:3001

Using Variables

// Next.js - server side
const apiKey = process.env.API_KEY;

// Next.js - client side (must be prefixed)
const publicUrl = process.env.NEXT_PUBLIC_API_URL;

Serverless Functions

API Routes (Next.js App Router)

// app/api/users/route.ts
import { NextRequest, NextResponse } from 'next/server';

export async function GET(request: NextRequest) {
  const users = await getUsers();
  return NextResponse.json(users);
}

export async function POST(request: NextRequest) {
  const body = await request.json();
  const user = await createUser(body);
  return NextResponse.json(user, { status: 201 });
}

API Routes (Pages Router)

// pages/api/users.ts
import type { NextApiRequest, NextApiResponse } from 'next';

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse
) {
  if (req.method === 'GET') {
    const users = await getUsers();
    return res.json(users);
  }

  if (req.method === 'POST') {
    const user = await createUser(req.body);
    return res.status(201).json(user);
  }

  res.setHeader('Allow', ['GET', 'POST']);
  res.status(405).end(`Method ${req.method} Not Allowed`);
}

Standalone Functions

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

export default function handler(req: VercelRequest, res: VercelResponse) {
  return res.json({ message: 'Hello from Vercel!' });
}

Function Configuration

// app/api/heavy/route.ts
export const runtime = 'nodejs';
export const maxDuration = 60; // seconds
export const dynamic = 'force-dynamic';

export async function GET() {
  // Long-running operation
}

Edge Functions

Edge Runtime

// app/api/geo/route.ts
import { NextRequest, NextResponse } from 'next/server';

export const runtime = 'edge';

export async function GET(request: NextRequest) {
  const country = request.geo?.country ?? 'Unknown';
  const city = request.geo?.city ?? 'Unknown';

  return NextResponse.json({
    country,
    city,
    message: `Hello from ${city}, ${country}!`,
  });
}

Middleware

// middleware.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  // Check auth
  const token = request.cookies.get('token');

  if (!token && request.nextUrl.pathname.startsWith('/dashboard')) {
    return NextResponse.redirect(new URL('/login', request.url));
  }

  // Add headers
  const response = NextResponse.next();
  response.headers.set('x-custom-header', 'value');

  return response;
}

export const config = {
  matcher: ['/dashboard/:path*', '/api/:path*'],
};

Caching & ISR

Static Generation with Revalidation

// app/posts/page.tsx
export const revalidate = 3600; // Revalidate every hour

async function getPosts() {
  const res = await fetch('https://api.example.com/posts', {
    next: { revalidate: 3600 },
  });
  return res.json();
}

export default async function PostsPage() {
  const posts = await getPosts();
  return <PostList posts={posts} />;
}

On-Demand Revalidation

// app/api/revalidate/route.ts
import { revalidatePath, revalidateTag } from 'next/cache';
import { NextRequest, NextResponse } from 'next/server';

export async function POST(request: NextRequest) {
  const { path, tag, secret } = await request.json();

  if (secret !== process.env.REVALIDATE_SECRET) {
    return NextResponse.json({ error: 'Invalid secret' }, { status: 401 });
  }

  if (path) {
    revalidatePath(path);
  }

  if (tag) {
    revalidateTag(tag);
  }

  return NextResponse.json({ revalidated: true });
}

Redirects & Rewrites

vercel.json

{
  "redirects": [
    { "source": "/blog/:slug", "destination": "/posts/:slug", "permanent": true },
    { "source": "/old-page", "destination": "/new-page", "statusCode": 301 }
  ],
  "rewrites": [
    { "source": "/api/:path*", "destination": "https://api.example.com/:path*" },
    { "source": "/:path*", "destination": "/index.html" }
  ]
}

Next.js Config

// next.config.js
module.exports = {
  async redirects() {
    return [
      {
        source: '/old-blog/:slug',
        destination: '/blog/:slug',
        permanent: true,
      },
    ];
  },
  async rewrites() {
    return [
      {
        source: '/api/:path*',
        destination: 'https://api.backend.com/:path*',
      },
    ];
  },
};

Deployment

Preview Deployments

# Every push to non-production branch creates preview
git push origin feature-branch
# Creates: feature-branch-abc123.vercel.app

Production Deployment

# Via CLI
vercel --prod

# Via Git (push to main/master)
git push origin main

Rollback

# Via CLI
vercel rollback [deployment-url]

# Via Dashboard
# Deployments > ... > Promote to Production

Monitoring

Analytics

// app/layout.tsx
import { Analytics } from '@vercel/analytics/react';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        {children}
        <Analytics />
      </body>
    </html>
  );
}

Speed Insights

import { SpeedInsights } from '@vercel/speed-insights/next';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        {children}
        <SpeedInsights />
      </body>
    </html>
  );
}

Cron Jobs

// vercel.json
{
  "crons": [
    {
      "path": "/api/cron/daily",
      "schedule": "0 0 * * *"
    },
    {
      "path": "/api/cron/hourly",
      "schedule": "0 * * * *"
    }
  ]
}

// app/api/cron/daily/route.ts
import { NextRequest, NextResponse } from 'next/server';

export async function GET(request: NextRequest) {
  const authHeader = request.headers.get('authorization');

  if (authHeader !== `Bearer ${process.env.CRON_SECRET}`) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  // Run daily task
  await runDailyTask();

  return NextResponse.json({ success: true });
}

Best Practices

1. Use environment variables - Never commit secrets
2. Configure regions - Deploy close to users/data
3. Enable preview deployments - Test before production
4. Use ISR for dynamic content - Balance freshness and speed
5. Add monitoring - Analytics and Speed Insights

Common Mistakes

Mistake	Fix
Exposing secrets	Use env vars, not code
Large function bundles	Split into smaller functions
Missing NEXT_PUBLIC_ prefix	Prefix client-side vars
No error handling	Add try/catch in functions
Cold start issues	Use edge runtime when possible

Reference Files

• references/functions.md - Function patterns
• references/caching.md - Caching strategies
• references/domains.md - Custom domains