This article guides you through implementing a secure JWT-based authentication system in a Next.js application using the App Router, with HTTP-only cookies for enhanced security. We'll cover setting up the backend API, handling authentication, and securing routes.

Prerequisites

• Node.js (v18 or later)
• Next.js (v14 or later)
• Basic understanding of React and TypeScript

Step 1: Project Setup

First, create a new Next.js project with TypeScript:

npx create-next-app@latest my-auth-app --typescript --app
cd my-auth-app

Install required dependencies:

npm install jsonwebtoken bcryptjs cookie

Step 2: Setting Up Environment Variables

Create a .env.local file in the root directory to store sensitive information: