IdentityServer is free for development, testing and personal projects, but production use requires a license.


There are three license editions which include different features.

Starter Edition

The Starter edition includes the core OIDC and OAuth protocol implementation. This is an economical option that is a good fit for organizations with basic needs. It’s also a great choice if you have an aging IdentityServer4 implementation that needs to be updated and licensed. The Starter edition includes all the features that were part of IdentityServer4, along with support for the latest .NET release, improved observability through OTEL support, and years of bug fixes and enhancements.

Business Edition

The Business edition adds additional features that go beyond the core protocol support included in the Starter edition. This is a popular license because it adds the most commonly needed tools and features outside a basic protocol implementation. Feature highlights include our backend-for-frontend security framework for SPAs, support for server side sessions, and automatic signing key management.

Enterprise Edition

Finally, the Enterprise edition includes everything in the Business edition and adds support for features that are typically used by enterprises with particularly complex architectures or that handle particularly sensitive data. Highlights include resource isolation, the OpenId Connect CIBA flow, and dynamic federation. This is the best option when you have a specific threat model or architectural need for these features.

License Key

The license key can be configured in one of two ways:

  • Via a well-known file on the file system
  • Programmatically in your startup code

File System

IdentityServer looks for a file named Duende_License.key in the ContentRootPath. If present, the content of the file will be used as the license key.


If you prefer to load the license key programatically, you can do so in your startup code. This allows you to use the ASP.NET configuration system to load the license key from any configuration provider, including environment variables, appsettings.json, an external configuration service such as Azure App Configuration, etc.

The AddIdentityServer method accepts a lambda expression to configure various options in your IdentityServer, including the LicenseKey. Set the value of this property to the content of the license key file.

public void ConfigureServices(IServiceCollection services)
    services.AddIdentityServer(options =>
        options.LicenseKey = "eyJhbG..."; // the content of the license key file

License Validation and Logging

The license is validated at startup and during runtime. All license validation is self-contained and does not leave the host. There are no outbound calls related to license validation.

Startup Validation

At startup, IdentityServer first checks for a license. If there is no license configured, IdentityServer logs a warning indicating that a license is required in a production deployment. You can ignore these messages in non-production environments.

Next, assuming a license is configured, IdentityServer compares its configuration to the license. If there are discrepancies between the license and the configuration, IdentityServer will write log messages indicating the nature of the problem.

Runtime Validation

Most common licensing issues, such as expiration of the license or configuring more clients than is included in the license do not prevent IdentityServer from functioning. We trust our customers and we don’t want a simple oversight to cause an outage. However, some features will be disabled at runtime if your license does not include them, including:

  • Server Side Sessions
  • DPoP
  • Resource Isolation
  • PAR
  • Dynamic Identity Providers
  • CIBA

Again, the absence of a license is permitted for development and testing, and therefore does not disable any of these features.


We understand that when IdentityServer is redistributed, log messages from the licensing system are not likely to be very useful to your redistribution customers. For that reason, in a redistribution the severity of log messages from the license system is turned all the way down to the trace level. We also appreciate that it might be cumbersome to deploy updated licenses in this scenario, especially if the deployment of your software does not coincide with the duration of the IdentityServer license. In that situation, we ask that you update the license key at the next deployment of your software to your redistribution customers. Of course, you are always responsible for ensuring that your license is renewed.

Log Severity

The severity of the log messages described above depend on the nature of the message and the type of license.

Type of Message Standard License Redistribution License (development*) Redistribution License (production*)
Startup, missing license Warning Warning Warning
Startup, license details Debug Debug Trace
Startup, valid license notice Informational Informational Trace
Startup, violations Error Error Trace
Runtime, violations Error Error Trace

* as determined by IHostEnvironment.IsDevelopment()