🚪🔐 OAuth Isn’t Your Login System — Here’s Why (and What You Should Use Instead)

In the world of modern web and mobile applications, chances are you've come across buttons like:

🟦 Login with Facebook

🔴 Sign in with Google

🐙 Connect with GitHub

They look sleek, feel easy, and save users from creating yet another password. But here's a common misconception:

🤔 "OAuth is for login, right?"

❌ Wrong. OAuth was never built for authentication.

Let’s break it down — with clarity, color, and a touch of geeky charm. 🎨✨

🧠 What is OAuth Actually?

OAuth (short for Open Authorization) is a standard protocol that lets apps access your resources on other services without needing your password. It’s all about delegated authorization.

Imagine this:

You use an app that needs access to your Google Calendar. Instead of handing over your Google password (😱), you let Google give that app just enough permission to read your events. That's OAuth in action.

📌 Core Goal of OAuth:

✅ Authorize third-party apps to access user-owned resources (like calendars, photos, contacts)

❌ Not for authenticating who the user is

🔓 So Why Is OAuth Used for "Login"?

Because... we (developers) got creative. 🎨

OAuth became popular because it let users skip registration forms and just "log in" with existing accounts (like Google or Facebook).

Apps started doing this:

Redirect to Google
Get access token
Use the token to call Google's userinfo endpoint
Identify the user
Treat it as a sign-in

But here's the issue:

⚠️ OAuth doesn't define how to verify identity. It just lets you access things.

So when you use OAuth alone for login, you're kind of building a login system on top of something that wasn’t designed for it. 🏗️

🎯 Enter OpenID Connect (OIDC): The Real Login Protocol

To fix this, OpenID Connect (OIDC) was created — a secure identity layer on top of OAuth 2.0.

🔑 What OIDC Adds:

ID Tokens (usually in JWT format): Say who the user is
Standard scopes like openid, email, profile
UserInfo endpoint to fetch structured identity data
Well-defined flows for authentication

🔍 In Short: OAuth vs OpenID Connect
🟡 OAuth 2.0 is used for authorization — it lets apps get access to a user's resources (like calendar, contacts, files) without needing their password.

🟢 OpenID Connect (OIDC) is used for authentication — it helps apps verify who the user is, using identity tokens and standard user info.

So remember:

✅ OAuth = “Can this app access my stuff?”
✅ OIDC = “Who is this person using the app?”

When you see “Login with Google”, it’s most likely using OIDC, not pure OAuth.

👎 Dangers of Using OAuth for Login (Without OIDC)

Using OAuth alone for authentication is risky. Here’s why:

⚠️ No standardized ID — How do you know the access_token belongs to the user?

⚠️ Token misuse — Access tokens are for resources, not for identity.

⚠️ Phishing risk — Without proper ID token validation, you're vulnerable to impersonation.

If you're building login flows using plain OAuth... you’re playing with 🔥.

✅ What You Should Do

Use an OIDC-compliant Identity Provider (IdP) like:

🟢 Google
🔵 Microsoft Azure AD
🟣 Auth0
🟡 Okta
🐙 GitHub (partially OIDC)

Implement using an OIDC client library (like oidc-client-ts for frontend or passport-openidconnect for Node.js).

Let the Identity Provider handle sign-in and give you an ID token so you know exactly who the user is.

📦 TL;DR: Quick Recap

Concept	Purpose	Protocol
OAuth	🔓 Authorization (Access user’s stuff)	OAuth 2.0
OIDC	👤 Authentication (Who is the user?)	OpenID Connect
Sign Up / Sign In	👋 Onboarding and Identity	Built on top of OIDC

🤹‍♀️ Final Thoughts: Use the Right Tool

OAuth is powerful — it lets apps access user resources securely. But using it for login is like using a screwdriver to hammer a nail — it kinda works, but you’ll break something eventually. 🪛🔨

For real sign-in functionality:

👉 Use OpenID Connect — the protocol built for that job.

Now the next time someone says,