IdentityServer is an extensible OpenID Connect and OAuth 2.0 framework for .NET applications, used by teams building their own identity and access infrastructure. It supports single sign-on, token issuance, API authorization, and custom authentication workflows.
💡 Pick it for a free, feature-rich self-hosted IAM platform with SAML, federation, and a mature administration console.
Keycloak is an open-source Identity and Access Management solution aimed at modern applications and services.
Free and open-source
💡 Pick it when you want production-ready hosted authentication without running identity infrastructure.
Auth0 provides a comprehensive platform for authentication and authorization.
Free tier available. Paid plans start at $23/month.
💡 Choose it for enterprise-grade customer IAM, governance, and scale with managed operations.
Okta Customer Identity Cloud is a managed customer identity and access management service for consumer and business applications. It supports branded login,...
Free tier up to 10,000 MAU; paid pricing varies
💡 Pick it for a self-hostable customer IAM product with a richer admin experience and user features.
FusionAuth is a complete identity and access management tool that provides authentication, authorization, and user management for any app.
Free for unlimited users, with paid support options
Microsoft
💡 Choose it when your applications already run on Azure and need managed customer or partner identity.
Microsoft Entra External ID is Microsoft's managed identity service for customer and partner applications. It provides branded sign-in, social and enterprise federation,...
Free tier; paid per monthly active user
💡 Pick it for modern open-source IAM with multi-tenancy, passkeys, and a hosted-or-self-hosted deployment choice.
ZITADEL is an open-source identity and access management platform for developers building customer-facing and workforce applications. It provides OAuth 2.0, OpenID Connect,...
Free tier; paid plans from $100/mo
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