Pros of IdentityServer4

• Open-source and free for commercial use
• Extensive community support and contributions
• Well-established and mature project with a long history

Cons of IdentityServer4

• No longer actively maintained
• Limited future updates and security patches
• Lack of official support for newer technologies and standards

Code Comparison

IdentityServer4:

services.AddIdentityServer()
    .AddInMemoryClients(Config.Clients)
    .AddInMemoryApiScopes(Config.ApiScopes)
    .AddInMemoryIdentityResources(Config.IdentityResources)
    .AddTestUsers(Config.Users);

DuendeSoftware/products:

services.AddIdentityServer()
    .AddInMemoryClients(Config.Clients)
    .AddInMemoryApiScopes(Config.ApiScopes)
    .AddInMemoryIdentityResources(Config.IdentityResources)
    .AddTestUsers(Config.Users)
    .AddDeveloperSigningCredential();

The code comparison shows that both projects have similar setup processes, with DuendeSoftware/products offering additional features like the developer signing credential. While IdentityServer4 is a well-established open-source solution, DuendeSoftware/products (Duende IdentityServer) is actively maintained and provides ongoing support and updates. However, Duende IdentityServer requires a commercial license for use in production environments.

Pros of OpenIddict

• Open-source and free to use
• Highly customizable and extensible
• Supports a wide range of authentication scenarios

Cons of OpenIddict

• Less comprehensive documentation compared to Duende
• May require more setup and configuration
• Limited commercial support options

Code Comparison

OpenIddict:

services.AddOpenIddict()
    .AddCore()
    .AddServer()
    .AddValidation();

Duende IdentityServer:

services.AddIdentityServer()
    .AddInMemoryClients(Config.Clients)
    .AddInMemoryApiScopes(Config.ApiScopes)
    .AddInMemoryIdentityResources(Config.IdentityResources);

OpenIddict offers a more modular approach, allowing developers to add only the components they need. Duende IdentityServer provides a more opinionated setup with built-in configurations.

Both projects are robust OpenID Connect and OAuth 2.0 frameworks for ASP.NET Core. OpenIddict is a free, open-source solution with great flexibility, while Duende IdentityServer offers a commercial product with professional support and more comprehensive documentation. The choice between them depends on project requirements, budget, and the level of customization needed.

Pros of azure-activedirectory-identitymodel-extensions-for-dotnet

• Specifically designed for Azure Active Directory integration
• Extensive documentation and Microsoft support
• Free and open-source

Cons of azure-activedirectory-identitymodel-extensions-for-dotnet

• Limited to Microsoft ecosystem and Azure AD
• May have a steeper learning curve for non-Microsoft developers
• Less flexibility for custom identity scenarios

Code Comparison

azure-activedirectory-identitymodel-extensions-for-dotnet:

var tokenValidationParameters = new TokenValidationParameters
{
    ValidateIssuer = true,
    ValidIssuer = "https://sts.windows.net/{tenantId}/",
    ValidateAudience = true,
    ValidAudience = "{clientId}"
};

products:

var options = new IdentityServerOptions
{
    IssuerUri = "https://myissuer.com",
    SigningCredential = new SigningCredentials(key, SecurityAlgorithms.RsaSha256)
};

The azure-activedirectory-identitymodel-extensions-for-dotnet library focuses on token validation for Azure AD, while products (Duende IdentityServer) provides a more comprehensive identity server solution with greater customization options. The former is ideal for Azure AD integration, while the latter offers more flexibility for various identity scenarios across different platforms.

Pros of Hydra

• Open-source and free to use, with a large community and extensive documentation
• Supports multiple databases (PostgreSQL, MySQL, CockroachDB) out of the box
• Highly scalable and designed for cloud-native environments

Cons of Hydra

• Steeper learning curve compared to Duende products
• Less comprehensive feature set for enterprise-level identity management
• May require more configuration and setup for advanced scenarios

Code Comparison

Hydra (Go):

import "github.com/ory/hydra/client"

c := client.NewHTTPClientWithConfig(nil, &client.TransportConfig{
    Schemes:  []string{"http", "https"},
    Host:     "localhost:4444",
    BasePath: "/",
})

Duende IdentityServer (C#):

services.AddIdentityServer()
    .AddInMemoryClients(Config.Clients)
    .AddInMemoryIdentityResources(Config.IdentityResources)
    .AddInMemoryApiScopes(Config.ApiScopes)
    .AddInMemoryApiResources(Config.ApiResources);

Both repositories provide OAuth 2.0 and OpenID Connect implementations, but Hydra focuses on being a lightweight, cloud-native solution, while Duende products offer a more comprehensive suite for enterprise identity management. Hydra's code tends to be more low-level and flexible, while Duende's abstractions provide a simpler setup for common scenarios in the .NET ecosystem.

Pros of Keycloak

• Open-source and free to use, with a large community and extensive documentation
• Supports a wide range of protocols and features out-of-the-box
• Highly customizable and extensible through themes and plugins

Cons of Keycloak

• Can be complex to set up and configure for advanced scenarios
• Performance may be less optimized compared to commercial solutions
• Limited official support options, relying mainly on community assistance

Code Comparison

Keycloak (Java):

public class KeycloakSecurityContext implements SecurityContext {
    private final AccessToken token;
    private final String tokenString;
    private final AuthorizationContext authorizationContext;
    // ...
}

Duende IdentityServer (C#):

public class SecurityContext : ISecurityContext
{
    public ClaimsPrincipal User { get; set; }
    public string AccessToken { get; set; }
    public string RefreshToken { get; set; }
    // ...
}

Both projects provide security context objects, but Keycloak's implementation is more focused on token-based authentication, while Duende IdentityServer offers a more general-purpose approach with claims-based identity.