vercel-local-dev-loop

name	vercel-local-dev-loop
description	Configure Vercel local development with vercel dev, environment variables, and hot reload. Use when setting up a development environment, testing serverless functions locally, or establishing a fast iteration cycle with Vercel. Trigger with phrases like "vercel dev setup", "vercel local development", "vercel dev environment", "develop with vercel locally".
allowed-tools	Read, Write, Edit, Bash(vercel:*), Bash(npm:*), Bash(npx:*), Grep
version	1.18.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","vercel","development","testing","workflow"]
compatibility	Designed for Claude Code

Vercel Local Dev Loop

Overview

Run Vercel serverless functions and API routes locally using vercel dev. Covers environment variable management, hot reload, local testing patterns, and framework-specific dev servers.

Prerequisites

• Completed vercel-install-auth setup
• Project linked via vercel link
• Node.js 18+ with npm/pnpm

Instructions

Step 1: Pull Environment Variables

# Pull env vars from Vercel to local .env files
vercel env pull .env.development.local

# This creates .env.development.local with all Development-scoped vars:
# VERCEL="1"
# VERCEL_ENV="development"
# DATABASE_URL="postgres://..."
# API_SECRET="sk-..."

Step 2: Start Local Dev Server

# vercel dev starts a local server that emulates the Vercel platform
vercel dev

# Output:
# Vercel CLI 39.x.x — dev command
# > Ready on http://localhost:3000

# With a specific port
vercel dev --listen 8080

# With debug logging
vercel dev --debug

vercel dev provides:

• Serverless function emulation at /api/* routes
• Automatic TypeScript compilation
• vercel.json rewrites, redirects, and headers applied locally
• Environment variables loaded from .env*.local files
• Framework detection (Next.js, Nuxt, SvelteKit, etc.)

Step 3: Test Serverless Functions Locally

# Test your API route
curl http://localhost:3000/api/hello
# {"message":"Hello from Vercel Serverless Function!"}

# Test with POST body
curl -X POST http://localhost:3000/api/users \
  -H "Content-Type: application/json" \
  -d '{"name":"test","email":"[e-mail]"}'

# Test with query parameters
curl