Auth0 Guardian vs FusionAuth

Auth0 Guardian is a mobile app for completing multi-factor authentication on iOS and Android. During login, users can approve a push notification on an enrolled device or enter a temporary one-time password. Guardian-generated OTPs normally remain valid for 30 seconds. The app supports multiple languages and dialects, follows the device language by default, and offers system, light, and dark themes. Users can protect it with a passcode, passphrase, or device biometrics. Organizations can use Guardian SDKs to build similar applications or add Guardian capabilities to their own apps. Push delivery can use AWS SNS, Firebase Cloud Messaging, or Apple Push Notification service. Auth0 MFA API endpoints can enforce MFA at token endpoints and manage enrolled factors. Guardian is available through the Apple App Store and Google Play Store. The free plan is available; paid plans start at 35 /mo, with a 22-day trial.

FusionAuth is a Customer Identity and Access Management server for authentication, authorization, and user management. It supports username and password login, passkeys, one-time passwords, and external identity providers, including Apple, Facebook, Google, and Twitter. It implements OAuth 2.0, OpenID Connect, and SAML v2. Authorization includes role-based access across users, roles, groups, applications, and entities, plus fine-grained authorization integration. Teams can customize pages and messages and use lambda functions and webhooks. It can run locally, on-premises, in private or air-gapped cloud environments, or as a managed FusionAuth Cloud instance. The free Community Edition is self-hosted and unlimited, with no trial clock. Starter costs $162 a month billed annually and includes one connector and 100 machine-to-machine entities; Essentials and Enterprise cost $2,970 a month billed annually. FusionAuth supports Android, iOS, Linux, macOS, Windows, web, and API deployments.