# FAQ for Authentication

- [OTP Test Mode](/faq-for-authentication/otp-test-mode.md): Suppress message delivery and fix OTP for testing purposes
- [Tips for Apple App Store Review with Passwordless Login](/faq-for-authentication/passwordless-demo-user-for-apple-app-review.md): How to pass the Apple Store review process if your app uses passwordless login.
- [Phone Number Validation](/faq-for-authentication/phone-number-validation.md)
- [Skip Login Screen and Direct Users to Enterprise Login](/faq-for-authentication/how-to-use-social-enterprise-login-providers-without-authui.md): Learn how to take users directly to an external OAuth provider's authorization page without opening AuthUI login page.
- [Use the OAuth 2.0 State Parameter](/faq-for-authentication/how-to-use-the-oauth-2.0-state-parameter.md): Reference on what the OAuth 2.0 parameter is and how to use it in Authgear SDK.
- [Local Dev Setup for Connecting to Authgear SaaS in Cookie-based Auth](/faq-for-authentication/local-cookie-based-web-setup.md): Setting up the local development environment for websites that use cookie-based authentication.