Auth0 is an identity platform that handles login and access control for applications, so development teams do not have to build authentication themselves. It covers sign-up and login, social login with Google or Apple, multi-factor authentication, single sign-on for business customers and the security around all of it. Auth0 started in 2013 and has been part of Okta since 2021.
How Auth0 Works
Your application sends users to Auth0's login page (Universal Login), or embeds Auth0's login components. Auth0 verifies the user against the configured connection: a username and password database, a social provider, or a company's own identity provider. After a successful login, Auth0 returns tokens based on OAuth 2.0 and OpenID Connect: an ID token describing the user and an access token, usually a JWT, that your API checks on every request.
Key Features
- Social and passwordless login: Google, Apple, Microsoft and others, plus email magic links and one-time codes.
- Multi-factor authentication: authenticator apps, push notifications, SMS and passkeys.
- Enterprise SSO: business customers log in with their own identity provider via SAML or OIDC, such as Microsoft Entra ID or Okta.
- Organizations: B2B features for SaaS platforms where each customer has its own users, login options and branding, see multi-tenancy.
- Roles and permissions: role-based access control included in the tokens your API receives.
- Actions: small functions that run during login or sign-up, for example to enrich tokens or call your own systems.
- Attack protection: brute-force protection, breached password detection and bot detection.
When to Use Auth0
Auth0 fits when you need more than a basic login: enterprise SSO for B2B customers, several applications sharing one identity, strict security requirements, or a team that should spend its time on the product rather than on authentication. Pricing is based on the number of active users and features, with a free tier for small projects. For very simple apps, the login built into your framework may be enough; for full control or on-premise needs, self-hosted alternatives can be a better fit.
Alternatives
Common alternatives are Okta Workforce Identity for internal staff, Microsoft Entra ID for organisations on Microsoft 365, AWS Cognito for AWS-centred stacks, Keycloak as an open-source self-hosted option, and Clerk or Firebase Authentication for consumer apps. The right choice depends on your users, your cloud and how much you want to manage yourself.
How SemBricks Uses Auth0
We integrate Auth0 into SaaS platforms, web applications and mobile apps, and secure the APIs behind them, see custom API development. That includes per-customer SSO, roles that map to your product's permissions, and migrating existing users without forcing everyone to reset their password.
Frequently Asked Questions
Is Auth0 free?
There is a free tier for small numbers of users and basic features. Paid plans are priced by active users and features such as enterprise SSO and advanced MFA.
What is the difference between Auth0 and Okta?
Both are owned by Okta. Auth0 is aimed at developers building customer-facing applications; Okta Workforce Identity focuses on employees signing in to company tools.
Is Auth0 secure?
Auth0 handles password storage, MFA and attack detection to a high standard, which is usually more secure than a self-built login. Your application still has to validate tokens correctly and protect its own APIs.
Can existing users be migrated to Auth0?
Yes. Users can be imported in bulk, or migrated gradually as they log in, so they keep their password.