Duende Software is a software company based in San Francisco, California, USA. Their flagship product, IdentityServer, is a widely adopted OpenID Connect and OAuth 2.0 framework for ASP.NET and ASP.NET Core, providing robust solutions for modern authentication and authorization needs. Originally developed as a free open-source project, IdentityServer's evolution led to the founding of Duende Software in 2020—establishing a stronger commercial foundation to continue its development, deliver enterprise-grade security solutions, and support customers worldwide. Today, Duende empowers developers and organizations to implement secure, standards-based identity management across their applications.