Building a Scalable Authentication System: Lessons from My Experience

Authentication is the foundation of any modern application. When I built an authentication API as a service, I encountered multiple challenges—from ensuring security to handling large-scale user requests efficiently. Here’s what I learned.

Choosing the Right Authentication Method

There are multiple authentication approaches, but the choice depends on your use case:

• JWT (JSON Web Tokens): Best for stateless, distributed systems but requires careful token expiration management.
• Session-Based Authentication: More traditional but can be challenging to scale horizontally.
• OAuth 2.0: Essential for third-party integrations, such as Google or GitHub logins.

For our API service, we used JWTs with short-lived access tokens and long-lived refresh tokens, minimizing the risk of token theft while maintaining a smooth user experience.

Handling Scalability

One of the biggest challenges was scaling authentication efficiently. Some lessons learned:

• Rate Limiting & Bot Protection: Implementing tools like Redis-based rate limiting prevented brute-force attacks.
• Distributed Session Management: When scaling horizontally, maintaining user sessions across servers was tricky. We solved this with Redis for session storage.
• Load Balancing: Authentication requests were distributed across multiple servers using Nginx, ensuring system reliability.

Security Best Practices

Security was our top priority. Some key implementations:

import bcrypt from 'bcrypt'

const hashPassword = async (password) => {
  const saltRounds = 10
  return await bcrypt.hash(password, saltRounds)
}

const verifyPassword = async (password, hash) => {
  return await bcrypt.compare(password, hash)
}