OpenIddict vs. Duende IdentityServer
OpenIddict and Duende IdentityServer are both .NET OpenID Connect and OAuth stacks with the same hosting model: NuGet packages in an ASP.NET Core host you run. OpenIddict is a free, open-source library where you author the protocol endpoints yourself. Duende IdentityServer provides the endpoints out of the box, with commercial support and natively integrated advanced features. Choose OpenIddict for maximum flexibility without licensing costs. Choose Duende IdentityServer for a server you configure rather than assemble, with a support contract behind it.
OpenIddict and Duende IdentityServer are both standards-compliant OpenID Connect and OAuth stacks for .NET. This is a comparison of two well-regarded projects that make different, deliberate design choices, not a case of one being better than the other.
The core difference is how much the framework does for you. The hosting model is the same: both are NuGet packages running in an ASP.NET Core host, a dedicated identity host that is separate from the applications it secures. OpenIddict is a flexible, event-driven library that integrates deeply with the ASP.NET Core authentication stack. In the common setup you author your own authorization, token, and logout endpoints (using OpenIddict's pass-through model) and wire in its managers. Duende IdentityServer provides the protocol endpoints out of the box, and you implement the interactive UI and your claim logic, then configure clients and resources.
This comparison was made on August 24, 2026, against current OpenIddict and Duende IdentityServer v8 releases. Both projects are actively developed and their functionality changes regularly, so the comparison may not be fully accurate at the time of reading.
How Do OpenIddict and Duende IdentityServer Compare?
Both stacks implement the core OpenID Connect and OAuth specification family (authorization code + PKCE, client credentials, device flow, introspection, revocation, and more). Check each project's documentation for the current status of specific RFCs rather than assuming. The comparison that matters is architectural:
| Capability / Aspect | OpenIddict | Duende IdentityServer |
|---|---|---|
| Protocol endpoints | You author them (pass-through model) | Provided out of the box |
| Interactive UI (login, consent) | You build it | You build it (same for both) |
| Extensibility model | Granular event handler pipeline | Services ( |
| Default access token format | JWTs by default; reference tokens optional | Signed JWTs by default; reference tokens optional |
| Stores | EF Core / MongoDB built-in, custom possible | EF Core built-in, custom possible |
| User management | Bring your own (commonly ASP.NET Identity) | ASP.NET Identity or User Management (passkeys, TOTP, OTP) |
| Server-side sessions | Assemble yourself | |
| Dynamic auth providers | Assemble yourself | |
| Automated signing key rotation | Assemble yourself | |
| OpenTelemetry observability | Via ASP.NET Core instrumentation | Native support (metrics, traces, and logs) |
| License | Free, open source (community project) | Commercial (free for dev/test; Community Edition for qualifying organizations) |
| Support | Community; commercial through project sponsorship | Commercial support from Duende |
How Do OpenIddict Concepts Map to Duende IdentityServer?
| OpenIddict | Duende IdentityServer | Notes |
|---|---|---|
| Application ( |
| |
| | The same properties on Client |
|
| Permissions (endpoints / grant types / scopes) | | Duende grants endpoint access implicitly from the grant types |
| Scope ( | Duende splits API scopes from identity resources | |
| | |
|
| | |
|
| Your | Built-in endpoints + your UI | The biggest structural change |
| Event handler pipeline | |
|
| EF entities ( | | Different schema. Let live tokens expire rather than migrating them. If you issue long-lived refresh tokens, shorten their lifetime before cutover or plan a brief re-authentication window |
When Is OpenIddict the Right Fit for You?
OpenIddict fits when you want a free, open-source library with maximum control over the request pipeline and are comfortable owning more of the plumbing yourself. It is a strong choice for teams who value that flexibility and don't need a commercial support relationship.
Duende IdentityServer fits when you'd rather configure a server than assemble one, want the protocol endpoints and their edge cases handled for you, and value commercial support, a long-term maintenance commitment, and a well-trodden path for demanding scenarios such as PAR, DPoP, CIBA, dynamic providers, and server-side sessions. The licensing cost buys support and a supported feature set. Whether that trade is worth it depends on your team and risk profile.
One migration detail to check: OpenIddict's default tokens are opaque reference tokens protected by ASP.NET Core Data Protection, though it can also be configured to issue JWTs, whereas Duende issues signed JWTs by default. If you move, confirm what your current OpenIddict deployment actually issues and map accordingly rather than assuming.