Enterprise SAML SSO in ASP.NET Core: The Complete Integration Guide for 2026

ASP.NET Core, widely used by professional developers, lacks native support for SAML 2.0, presenting a challenge for implementing enterprise SAML Single Sign-On (SSO). This guide outlines a solution using SSOJet's OIDC flow, which integrates seamlessly with ASP.NET Core's AddOpenIdConnect stack, bypassing the need for direct SAML coding. The process involves redirecting users to SSOJet's hosted login page, handling SAML XML parsing and authentication, and returning normalized user claims to create ASP.NET Core sessions without additional SAML library dependencies. Key considerations include setting SameSite cookies to Lax to avoid breaking SSO, implementing proper caching for IClaimsTransformation to prevent performance issues, and ensuring correct middleware order behind proxies. SSOJet's flat-rate pricing simplifies multi-tenant SSO costs, while its OIDC hosted page provides a customizable, enterprise-friendly login experience. The guide emphasizes the importance of understanding production failure modes and offers strategies for efficient multi-tenant onboarding and compliance, leveraging SSOJet's infrastructure and certifications.