Alex Spinov

Posted on Mar 27

Auth0 Has a Free Tier — Add Login, SSO, and Multi-Factor Auth to Any App Without Building It Yourself

#security #webdev #tutorial #api

Every developer has tried to build authentication from scratch at least once. Password hashing, session management, OAuth flows, password reset emails, rate limiting, brute force protection...

Then you realize Auth0 gives you all of that for free. Up to 25,000 monthly active users. No credit card.

What You Get for Free

25,000 monthly active users
Social login — Google, GitHub, Facebook, Apple, Twitter
Passwordless — magic links and OTP via email/SMS
Multi-factor authentication — TOTP, SMS, email
Universal Login — hosted login page, customizable
Role-based access control — permissions and roles out of the box
Up to 2 organizations — B2B multi-tenancy support
Unlimited logins — no per-login charges

Quick Start (5 Minutes)

1. Create an Application

2. Add Login to a React App

npm install @auth0/auth0-react

import { Auth0Provider, useAuth0 } from "@auth0/auth0-react";

function App() {
  return (
    <Auth0Provider
      domain="YOUR_DOMAIN.auth0.com"
      clientId="YOUR_CLIENT_ID"
      authorizationParams={{ redirect_uri: window.location.origin }}
    >
      <LoginButton />
    </Auth0Provider>
  );
}

function LoginButton() {
  const { loginWithRedirect, logout, user, isAuthenticated } = useAuth0();

  if (isAuthenticated) {
    return (
      <div>
        <p>Welcome, {user.name}!</p>
        <button onClick={() => logout()}>Log out</button>
      </div>
    );
  }

  return <button onClick={() => loginWithRedirect()}>Log in</button>;
}

That is it. Google login, GitHub login, email/password — all work out of the box.

3. Protect an API (Node.js)

import express from "express";
import { auth } from "express-oauth2-jwt-bearer";

const app = express();

const checkJwt = auth({
  audience: "https://your-api.example.com",
  issuerBaseURL: "https://YOUR_DOMAIN.auth0.com/",
});

app.get("/api/private", checkJwt, (req, res) => {
  res.json({ message: "This is protected", user: req.auth.payload.sub });
});

app.listen(3000);

4. Python (Flask)

from authlib.integrations.flask_client import OAuth

oauth = OAuth(app)
auth0 = oauth.register(
    "auth0",
    client_id="YOUR_CLIENT_ID",
    client_secret="YOUR_SECRET",
    api_base_url=f"https://YOUR_DOMAIN.auth0.com",
    access_token_url=f"https://YOUR_DOMAIN.auth0.com/oauth/token",
    authorize_url=f"https://YOUR_DOMAIN.auth0.com/authorize",
    client_kwargs={"scope": "openid profile email"},
)

@app.route("/login")
def login():
    return auth0.authorize_redirect(redirect_uri="http://localhost:3000/callback")

Why Not Build Auth Yourself?

A security engineer I worked with put it bluntly:

"We spent 3 months building custom auth. Then we got breached through a session fixation bug that Auth0 had patched 4 years ago. We migrated to Auth0 in a week. Should have started there."

Building auth means you are responsible for:

OWASP top 10 vulnerabilities
Token rotation and revocation
Brute force detection
Credential stuffing protection
GDPR compliance for user data
Password breach detection (Have I Been Pwned integration)

Auth0 handles all of this on the free tier.

Free Plan Limits

Feature	Free Tier
Monthly Active Users	25,000
Social Connections	Unlimited
Custom Domains	No
Organizations	2
Machine-to-Machine Tokens	1,000/month
Actions (serverless hooks)	3
MFA	Yes
Passwordless	Yes

The Bottom Line

25,000 MAU is enough for most startups well past seed stage. You will not need to pay until your app is already making money.

Stop building auth. Ship your actual product instead.

Need to scrape authenticated websites or extract data behind logins? Check out my web scraping tools on Apify — handle any auth flow automatically.

Building something custom? Email me at spinov001@gmail.com

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