Authentication is one of those foundational components of web development that looks deceptively simple on the surface. Slap together a signup form, generate a token, throw it in local storage, and you are good to go, right?
Wrong. In a recent breakdown on his channel, engineer Mehul Mohan pulled back the curtain on common authentication patterns, exposing why many modern implementations—even those used in production—are fundamentally flawed. If you want to ensure your user data is truly secure, it is time to unlearn some modern “best practices” and adopt a battle-tested, senior-engineer mindset.
Here are the key architectural takeaways to fix your auth system before it becomes a vulnerability.
1. Stop Relying Blindly on Auth Vendors
Third-party auth providers offer incredible convenience, but absolute dependency on external vendors abstracts away safety and implementation logic. When you build your own core auth boundaries, you retain full control over your security policy, data sovereignty, and response measures during an incident. Vendor convenience should never replace an architectural understanding of your system’s safety lines.
2. Eliminate “Auth Bloat”
Many teams overcomplicate the login and signup experience by offering half a dozen OAuth providers alongside standard credentials. While it feels like a UX win, every single authentication method adds a new surface area for threats, misconfigurations, and vulnerabilities.
Rule of Thumb: Keep your auth options lean. Fewer entry points mean a drastically reduced attack surface.
3. The Hidden Pitfalls of Email Verification
While email authentication seems standard, relying heavily on magic links or open email validation loops can be an operational nightmare. Without rigorous protections, malicious actors can abuse these endpoints to trigger scriptable spam attacks, leading to domain blacklisting and massive premium email API bills. If you implement email auth, ensure it is heavily guarded against automation.
4. Secure Your Standard Email + Password Flows
If you are sticking to a classic email and password configuration, it must be hardened at the gate:
- Hashing is Non-Negotiable: Passwords must always be securely hashed and salted on the backend.
- Whitelisting: Where applicable, whitelist trusted email domains to prevent burner account registration.
- Rate Limits + Captchas: Protect your endpoint from brute-force bots by layering automated captchas and strict rate-limiting policies directly onto your auth routes.
5. Move Away from Stateless JWT Auth
One of the most controversial yet critical pieces of advice is to stop using stateless JWT (JSON Web Token) authentication.
While stateless JWTs became incredibly popular for scalability, they present a massive security problem: invalidation. If a user’s token is stolen, you cannot easily revoke their access until the token naturally expires.
Instead, maintain explicit control over active sessions. Create a dedicated authentication/session table in your database. By querying the database table on auth calls, you retain the immediate power to kill a compromised session instantly.
6. Upgrade Your 2FA (Say Goodbye to SMS)
If you are still sending numeric codes via SMS for Two-Factor Authentication, your users are vulnerable to SIM-swapping attacks.
Senior architecture demands replacing SMS auth with Authenticator App TOTP (Time-Based One-Time Password) setups. While advanced features like Passkeys are optional additions to your roadmap, securing your baseline 2FA with an authenticator app is a necessity.
Architecture Checklist for Senior Devs
- Ensure user identities are anchored by strong, unique identifiers across database collections.
- Shift from stateless tokens to stateful, database-verified sessions.
- Minimize entry vectors down to essential, tightly monitored login options.
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