Should I build authentication myself?

No. Authentication is security-critical with many edge cases: password hashing, session management, rate limiting, 2FA. Services like Clerk and Auth0 have teams dedicated to getting this right. Use them.

Clerk, Auth0, or Supabase Auth?

Clerk has the best developer experience and modern UI components. Auth0 is enterprise-grade with extensive features. Supabase Auth is great if you're already using Supabase. Clerk is the popular choice for new startups.

What does authentication cost?

Most services have generous free tiers. Clerk is free up to 10,000 monthly active users. Auth0 is free up to 7,000 users. Supabase Auth is free with their database. Paid plans scale with user count.

What is the difference between authentication and authorization?

Authentication verifies who users are (login). Authorization determines what they can do (permissions). Auth services handle authentication. You typically build authorization logic in your app based on user roles.

What social login providers should I support?

Start with Google—it has the widest reach. Add GitHub for developer products. Apple Sign-In is required for iOS apps. Facebook if your audience uses it. Don't over-add—each provider has maintenance overhead.

What are magic links?

Passwordless login via email links. Users enter their email, receive a link, click it, and they're logged in. More secure than passwords, better UX for many users. Most auth services support magic links.

OAuth lets users log in with existing accounts (Google, GitHub). Your app redirects to the provider, user approves, provider sends back a token. Auth services abstract this complexity—you just configure the providers.

Should I require two-factor authentication?

Offer it, but don't require it for all users—it adds friction. Require 2FA for admin accounts and sensitive operations. Auth services make 2FA easy to implement with TOTP apps or SMS.

How do I handle password resets?

Never build password reset yourself—it's a common vulnerability source. Auth services handle secure reset flows: send token via email, expire quickly, one-time use. Just configure the email templates.

What is session management?

Tracking logged-in users across requests. Sessions can be JWT tokens or server-side. Auth services handle session creation, validation, and expiration. Configure session duration based on your security needs.

How do I add authentication to my React/Next.js app?

Clerk and Auth0 provide React SDKs with hooks and components. Wrap your app in their provider, use their login components or hooks. Protected routes check auth state. Documentation walks through setup.

What about mobile app authentication?

Same providers work for mobile. Auth0, Firebase, and Clerk have iOS and Android SDKs. Handle token storage securely on device. OAuth flows work slightly differently on mobile but SDKs abstract this.

How do I migrate from one auth provider to another?

Painful but possible. Export user data (if provider allows), import to new provider, handle password migration (usually requires reset), and update your code. Plan carefully and migrate during low-traffic periods.

WorkOS focuses on enterprise features: SSO (Single Sign-On), directory sync, and compliance. If you're selling to enterprises that require SSO with their identity provider (Okta, Azure AD), WorkOS handles it.

How do I test authentication in development?

Auth services provide test modes and development environments. Create test users, use sandbox OAuth apps, and separate dev from production. Clerk and Auth0 have great local development workflows.

What are webhooks and why do I need them for auth?

Webhooks notify your app when auth events occur: user created, updated, deleted. Use them to sync user data to your database, send welcome emails, or trigger onboarding flows. Essential for keeping systems in sync.

How do I handle user data with GDPR?

Auth providers store user data in their infrastructure. Ensure your provider is GDPR-compliant. Implement data export and deletion features as required. Clerk and Auth0 provide user data APIs for compliance.

What is rate limiting and why does auth need it?

Rate limiting prevents brute force attacks by limiting login attempts. Auth services handle this automatically—blocking IPs after failed attempts. Without it, attackers could try unlimited passwords.

Back to all problems

Solution illustration for I need user authentication for my app

Critical Priority

Best User Authentication & Login Tools for Startup Apps

Secure authentication without the security headaches.

2-4 hours

Technical

About This Problem

User authentication is complex and security-critical. Modern auth services handle login, registration, password resets, social login, and security best practices—so you don't have to build it yourself.

You might have this problem if:

✓Building an app that needs user accounts
✓Don't want to store passwords yourself
✓Need social login (Google, GitHub, etc.)
✓Worried about security best practices
✓Need features like 2FA and magic links

Success Looks Like

Users can sign up and log in
Social login providers configured
Password reset flow working

Relevant For

pre-launch stagelaunch stagegrowth stage

Implementing authentication for your startup app is one of the most security-critical features you will build, which is exactly why you should not build it yourself. Modern auth services handle login, registration, password resets, social sign-in, and two-factor authentication out of the box. Compare the best authentication providers that let you add secure user accounts in hours, not weeks, with SDKs for every major framework.