Duende IdentityServer is a powerful OpenID Connect and OAuth 2.0 framework for ASP.NET Core, enabling secure authentication, authorization, and single sign‑on (SSO). Below is a curated list of 20 alternative IAM/SSO solutions that provide comparable features such as password management, federation, multi‑factor authentication, and developer‑friendly APIs.
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Open‑source identity and access management solution with SSO, social login, LDAP/AD federation, and fine‑grained authorization policies.
Cloud‑based identity platform offering universal login, passwordless, MFA, and extensive SDKs for modern applications.
Enterprise‑grade identity service with SSO, lifecycle management, adaptive MFA, and extensive integrations.
Microsoft’s cloud identity service for consumer‑facing apps, supporting OAuth2, OpenID Connect, social identity providers, and custom policies.
Developer‑focused IAM platform offering SSO, password hashing, MFA, social login, and a powerful REST API.
Secure SSO and identity management platform with adaptive MFA, directory integration, and extensive app catalog.
Enterprise identity platform delivering SSO, MFA, API security, and identity governance for hybrid environments.
Managed user directory and authentication service with SAML, OIDC, social identity federation, and built‑in MFA.
Google Cloud’s identity solution offering OAuth2, OpenID Connect, and integration with Google Workspace and external IdPs.
Comprehensive IAM suite with SSO, MFA, risk‑based authentication, and lifecycle management for cloud and on‑premises.
Directory‑as‑a‑Service providing SSO, LDAP, RADIUS, and device management with cloud‑native scalability.
Privileged access management platform with SSO, MFA, and zero‑trust security controls.
Open‑source, cloud‑native authentication service offering passwordless, social login, and fine‑grained access control.
Open‑source IAM suite supporting SAML, OpenID Connect, UMA, and strong authentication mechanisms.
Legacy open‑source .NET Core framework for OAuth2/OIDC, still maintained by the community after Duende’s commercial fork.
Focused on MFA and passwordless verification, can be combined with existing IdPs for two‑factor authentication.
Identity provider delivering adaptive authentication, SSO, and risk‑based access controls.
Zero‑trust access solution for servers and APIs, providing short‑lived certificates and SSO integration.
Developer‑first authentication platform offering passwordless, magic links, OTP, and embedded login experiences.
Enterprise identity service with SSO, conditional access, MFA, and integration across Microsoft 365 and third‑party apps.