There are several popular and widely trusted authentication apps available, including:

• Google Authenticator: Developed by Google, it generates time-based one-time passwords (TOTPs) for two-factor authentication (2FA).
• Microsoft Authenticator: Offers similar functionality to Google Authenticator and supports Microsoft accounts, as well as other services that use TOTP for 2FA.
• LastPass Authenticator: Offers TOTP generation for LastPass accounts and other services, along with additional security features like push notifications.
• Duo Mobile: Offers TOTP generation along with push notifications and biometric authentication support for enhanced security.

The best authentication app for you may depend on factors such as compatibility with the services you use, additional features you may need, and personal preferences regarding user interface and ease of use.