Build Without Limits 

Start Without Cost

Duende IdentityServer is the go-to choice when you need complete control over your identity infrastructure. A standards-compliant OpenID Connect and OAuth 2.x framework for ASP.NET Core, trusted by 2,500+ organizations who need the flexibility to customize authentication flows, data storage, business logic, and deployment.

Free for development and testing. Only pay when you move to production.

Migrate from IdentityServer4 Start Building

Existing Users

Migrating from IdentityServer4

IdentityServer4 has not been supported since 2022. Security vulnerabilities are documented. .NET has moved on. Duende IdentityServer is the direct continuation, built by the same creators.

Migration Guide Free IS4 Upgrade Assessment

Getting Started

New to Duende IdentityServer

Need SSO? Machine-to-machine auth? Token security? API protection for your .NET applications? Start now at no cost. When you're ready for production, choose the tier that fits.

Quickstart Tutorials

infrastructure for the world's most demanding organizations

Trusted by 2,500 Security-Conscious Organizations

.NET-native. C#-first. Delivered via NuGet. Built by the creators of IdentityServer. The most widely deployed OpenID Connect and OAuth framework in the .NET ecosystem.

Build on Duende IdentityServer

Identity isn't just another layer of security - it's the foundation that makes progress possible. Duende gives developers the power to build.

Full control over everything. UI, UX, business logic, data, deployment. Your identity layer behaves exactly the way your architecture demands.
SDK, not SaaS. If what you want to achieve is doable in .NET, it's doable with IdentityServer.
Built on a bedrock of protocols. OAuth 2.0, OAuth 2.1, OpenID Connect, FAPI 2.0, DPoP, PAR, CIBA.
Runs anywhere. On-prem, cloud, containers, Kubernetes, Windows, Linux, air-gapped, behind a VPN. Your architecture dictates deployment
Now with modular add-ons. Extend your IdentityServer with User Management, SAML IdP, Financial-grade Security & Conformance, Automatic Key Management, and Multi-Issuer - exactly when your business needs them.

Migrating from a SaaS IdP

Evaluating Duende because your SaaS identity provider doesn’t have the right features, control, or budget for your needs? Here's what's different:

You own the code path. No black-box abstractions. Every capability is available based on your tier, not hidden behind opaque enterprise pricing.
Transparent cost. Annual licensing by tier that doesn’t punish your growth.
No vendor lock-in. Your identity infrastructure runs in your environment, on your terms. Migrate away anytime - your configuration, your data, your deployment.
The tradeoff is real. Duende is an SDK, not a managed service. You're responsible for deployment, operations, and upgrades. In return, you get absolute control, full customization, and transparent pricing.