TL;DR
OAuth delegates authentication to trusted providers like Google or GitHub. Passwordless uses email links, SMS codes, or passkeys directly. OAuth is more secure when users reuse weak passwords since provider handles auth. Passwordless gives you control but requires proper implementation. Use OAuth for simplicity; passwordless (especially WebAuthn) for maximum security without third-party dependencies.
OAuth and passwordless solve the password problem differently. OAuth trusts another provider to authenticate users. Passwordless eliminates passwords entirely using alternative factors. Both improve on traditional password auth, but with different security tradeoffs and implementation complexity.
Security Feature Comparison
| Security Aspect | OAuth | Passwordless |
|---|---|---|
| Password Reuse Risk | Eliminated | Eliminated |
| Phishing Resistance | Depends on provider | High (WebAuthn) / Low (email) |
| Third-Party Dependency | Yes (provider trust) | No (or email provider) |
| Account Recovery | Through provider | Your responsibility |
| User Data Access | Provider has data | You control data |
| MFA Built-in | If provider requires | Depends on method |
| Implementation Complexity | Lower (libraries) | Medium to High |
OAuth Security Model
Delegated Trust
OAuth delegates authentication to providers like Google, GitHub, or Microsoft. You trust these providers to authenticate users correctly. The security of your app depends on the security of these providers. If Google's authentication is compromised, accounts using Google OAuth are affected.
OAuth Advantages
Users benefit from the provider's security investment: MFA enforcement, fraud detection, and compromised credential monitoring. You don't manage passwords, reducing your attack surface. However, you depend on provider availability and policies. If Google suspends a user, they can't access your app.
Passwordless Security Model
Direct Authentication
Passwordless authenticates users directly without passwords. Methods include magic links (email), SMS codes, push notifications, or WebAuthn (passkeys). You control the entire authentication flow. Security depends on your implementation quality and the chosen method.
Passwordless Methods Ranked
- WebAuthn/Passkeys: Highest security, phishing-resistant, device-bound credentials
- Push Notifications: Good security, requires app installation
- Magic Links: Moderate security, depends on email security
- SMS Codes: Lowest security, vulnerable to SIM swapping
Choose OAuth When: You want simple implementation with strong security defaults. OAuth makes sense when users already have accounts with major providers and you trust those providers. Best for applications where quick onboarding matters and you don't need to own the authentication relationship.
Choose Passwordless When: You want to own the authentication relationship without third-party dependencies. WebAuthn provides the strongest security available. Best for applications requiring independence from social providers, enterprise environments, or when maximum security is required.
Implementation Security
OAuth Best Practices
- Validate state parameter to prevent CSRF
- Use PKCE for public clients
- Validate redirect URIs strictly
- Request minimal scopes needed
- Store tokens securely server-side
Passwordless Best Practices
- Use WebAuthn when possible for phishing resistance
- Short expiration for magic links (10-15 minutes)
- Rate limit authentication attempts
- Bind tokens to IP or session when possible
- Avoid SMS as the only option
Can I use both OAuth and passwordless?
Yes, many applications offer multiple authentication options. Users can choose OAuth for convenience or passwordless for independence. This increases accessibility while maintaining security for users who prefer either method.
Is OAuth less secure because it depends on third parties?
Not necessarily. Major OAuth providers invest heavily in security and may be more secure than your own implementation. The risk is dependency, not inherent insecurity. However, you trust them with authentication and some user data.
What's the most secure passwordless method?
WebAuthn (passkeys) is the most secure passwordless method. Credentials are cryptographically bound to domains, making phishing impossible. Magic links and SMS are convenient but have security limitations.
Secure Your Authentication
CheckYourVibe validates your OAuth and passwordless implementation for security issues.
Try CheckYourVibe Free