vercel-security-basics

name	vercel-security-basics
description	Apply Vercel security best practices for secrets, headers, and access control. Use when securing API keys, configuring security headers, or auditing Vercel security configuration. Trigger with phrases like "vercel security", "vercel secrets", "secure vercel", "vercel headers", "vercel CSP".
allowed-tools	Read, Write, Edit, Bash(vercel:*), Grep
version	1.18.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","vercel","security","headers","secrets"]
compatibility	Designed for Claude Code

Vercel Security Basics

Overview

Secure Vercel deployments with proper secret management, security headers, deployment protection, and access token hygiene. Covers environment variable scoping, Content Security Policy, and preventing common secret exposure patterns.

Prerequisites

• Vercel CLI installed and authenticated
• Access to Vercel dashboard
• Understanding of HTTP security headers

Instructions

Step 1: Secret Management with Environment Variables

# Add secrets scoped to specific environments
vercel env add DATABASE_URL production
vercel env add DATABASE_URL preview
vercel env add DATABASE_URL development

# Use 'sensitive' type — values hidden in dashboard and logs
vercel env add API_SECRET production --sensitive

# Via REST API
curl -X POST "https://api.vercel.com/v9/projects/my-app/env" \
  -H "Authorization: Bearer $VERCEL_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "key": "API_SECRET",
    "value": "sk-secret-value",
    "type": "sensitive",
    "target": ["production"]
  }'

Critical rule: Never prefix secrets with NEXT_PUBLIC_. Variables starting with NEXT_PUBLIC_ are inlined into the client JavaScript bundle and visible to anyone.

Step 2: Security Headers via vercel.json

{
  "headers": [
    {
      "source": "/(.*)",
      "headers": [
        { "key": "X-Content-Type-Options", "value"