Kinde

Seamless Integration of SSO, MFA, passwordless auth and more. Includes SDKs for frontend and backend apps. Free up to 1000 MAUs and five identity providers.

Open source user authentication that natively integrates into your app - enabling you to get started quickly while controlling the user and developer experience. Free for up to 5000 MAUs.

Open-source authentication that doesn't suck. The most developer-friendly solution, getting you started in just five minutes. Self-hostable for free, or offers a managed SaaS version with 10k free Monthly Active Users.

Auhtorization-as-a-service provider platform enabling RBAC, ABAC, and ReBAC for scalable microservices with real-time updates and a no-code policy UI. A 1000 Monthly Active User free tier.

AuthN/AuthZ/OAuth2.0/Zero Trust managed security platform. Forever free developer accounts with all security features, unlimited team members, 200 daily active users, and 25k/mo permission checks.

MojoAuth makes it easy to implement Passwordless authentication on your web, mobile, or any application in minutes.

Two-factor authentication (2FA) by push notifications, free for ten users, VPN, Websites, and SSH

Keycloak Identity and Access Management as a Service. Free up to 100 users and one realm.