Authentication & Authorization APIs let you add authentication & authorization capabilities without building from scratch. Every entry below is profiled with trust signals — pricing model, authentication requirements, CORS support, rate limits, and live uptime checks — so you can compare options and pick production-safe choices instead of guessing from a link list.
| API | Pricing | Auth | CORS | Health | |
|---|---|---|---|---|---|
| Auth0 Easy to implement, adaptable authentication and authorization platform | Freemium | API Key | Yes | Profile | |
| Auth0 API Auth0 API for universal login, social/enterprise SSO, MFA, passwordless, user management, and JWT-based authorization across any app type. | Freemium | OAuth | Yes | Profile | |
| Auth0 Management API Management API for Auth0 users, clients, roles, organizations, connections, and tenants. | Freemium | API Key | Yes | Profile | |
| Clerk Drop-in React components for authentication and authorization | Freemium | API Key | Yes | Profile | |
| Clerk API Clerk API for user authentication: sign-in/sign-up, MFA, organization management, webhooks, and embeddable UI components. | Freemium | API Key | Yes | Profile | |
| Clerk Backend API Backend API for users, organizations, sessions, invitations, and authentication resources. | Freemium | API Key | Yes | Profile | |
| Corbado Passkey-first authentication | Freemium | API Key | Yes | Profile | |
| Descope API Descope API: passwordless authentication with magic links, passkeys, social login, MFA, and user management. | Freemium | API Key | Yes | Profile | |
| Descope Management API Authentication and user management APIs for flows, users, tenants, roles, and SSO. | Freemium | API Key | Yes | Profile | |
| FusionAuth API Identity platform APIs for users, applications, tenants, registrations, and auth flows. | Freemium | API Key | Yes | Profile | |
| GetOTP Implement OTP flow quickly | Freemium | API Key | No | Profile | |
| Kinde Authentication for modern applications. Integrates in minutes and free up to 7,500 MAU | Freemium | OAuth | No | Profile | |
| Logto Management API Identity management API for users, organizations, applications, roles, and permissions. | Freemium | API Key | Yes | Profile | |
| Micro User Service API User management and authentication | Unknown | API Key | No | Profile | |
| MojoAuth Secure and modern passwordless authentication platform | Freemium | API Key | Yes | Profile | |
| SAWO Labs API Simplify login and improve user experience by integrating passwordless authentication in your app | Unknown | API Key | Yes | Profile | |
| Stytch User infrastructure for modern applications | Freemium | API Key | No | Profile | |
| Stytch API Stytch API for passwordless authentication: magic links, email OTP, SMS, OAuth, B2B SSO, SCIM, and session management. | Freemium | API Key | No | Profile | |
| Warrant API APIs for authorization and access control | Unknown | API Key | Yes | Profile | |
| WorkOS API WorkOS API for enterprise SSO (SAML, OIDC), SCIM provisioning, organization management, audit logs, and directory sync. | Freemium | API Key | No | Profile |
Start with pricing and auth: free tiers and no-auth APIs are fastest to prototype with. Then check CORS if your app calls the API from the browser, and health before you commit — a great API that's been down for a week will block your launch. Each profile below shows all of these signals plus rate limits where documented.