Security is non-negotiable for SaaS applications. A single breach can destroy customer trust. This guide covers the essential security layers every SaaS must implement.

Authentication with NextAuth.js

import NextAuth from 'next-auth'
import Google from 'next-auth/providers/google'
import GitHub from 'next-auth/providers/github'
import { PrismaAdapter } from '@auth/prisma-adapter'

const handler = NextAuth({
  adapter: PrismaAdapter(prisma),
  providers: [
    Google({ clientId: process.env.GOOGLE_CLIENT_ID!, clientSecret: process.env.GOOGLE_CLIENT_SECRET! }),
    GitHub({ clientId: process.env.GITHUB_CLIENT_ID!, clientSecret: process.env.GITHUB_CLIENT_SECRET! }),
  ],
  session: { strategy: 'jwt' },
  callbacks: {
    async jwt({ token, user }) {
      if (user) { token.role = user.role; token.tenantId = user.tenantId }
      return token
    },
    async session({ session, token }) {
      session.user.role = token.role as string
      return session
    },
  },
})
export { handler as GET, handler as POST }

Role-Based Access Control

Implement RBAC middleware that protects routes by role:

import { withAuth } from 'next-auth/middleware'

export default withAuth({
  callbacks: {
    async authorize({ token, req }) {
      const role = token?.role as string
      const roleAccess: Record<string, string[]> = {
        owner: ['/dashboard', '/settings', '/billing', '/team'],
        admin: ['/dashboard', '/settings', '/team'],
        member: ['/dashboard'],
        viewer: ['/dashboard'],
      }
      return roleAccess[role]?.some(r => req.nextUrl.pathname.startsWith(r)) || false
    },
  },
})

Data Encryption

Encrypt sensitive data at rest using AES-256-GCM for field-level encryption of PII, payment data, and API keys.

API Security

Protect API routes with rate limiting using Upstash Redis, input validation with Zod, and proper CORS configuration.

Security Headers

Configure X-Frame-Options, X-Content-Type-Options, HSTS, and CSP headers in next.config.js.

The Bottom Line

Security is a layered approach. The Auth Boilerplate from BreafIO provides complete authentication. The SaaS Starter Kit includes RBAC and tenant isolation. The API Boilerplate offers API security patterns. The Admin Dashboard Pro includes audit logging, and always encrypt sensitive data following OWASP guidelines.