What is Microsoft Entra External ID?

If your business runs customer-facing apps, you need a secure way for customers, partners, or citizens to sign up, sign in, reset passwords, and access APIs without building an identity platform from scratch. Microsoft Entra External ID is Microsoft’s current customer identity and access management platform for new implementations, while Azure AD B2C is now a legacy option for existing customers.

Microsoft Entra External ID in 2026

Microsoft Entra External ID is Microsoft’s modern identity platform for external users, including customer-facing application scenarios often called CIAM: Customer Identity and Access Management. It helps organizations add sign-up, sign-in, profile management, federation, token-based authentication, and access control to web, mobile, single-page, desktop, and API-based applications. It is managed through Microsoft Entra and Microsoft Azure services, and it uses standards such as OpenID Connect and OAuth 2.0, with SAML used where applicable for federation or application integration scenarios.

What happened to Azure AD B2C?

Azure Active Directory B2C, commonly known as Azure AD B2C or AAD B2C, was Microsoft’s earlier CIAM service. The branding is now dated, and the product is no longer the right default recommendation for new projects. Microsoft announced that Azure AD B2C is unavailable for purchase by new customers as of May 1, 2025. Existing Azure AD B2C customers can continue to operate their tenants, but new customer-facing identity projects should evaluate Microsoft Entra External ID instead. If you already use Azure AD B2C, the practical question is not whether it stops working tomorrow; it is when and how to plan a responsible migration or modernization path.

What can Microsoft Entra External ID do?

Microsoft Entra External ID can help applications support customer account creation, sign-in, password reset or passwordless-oriented sign-in patterns where supported, profile management, branded authentication experiences, federation with supported identity providers, and secure access to APIs. Typical scenarios include customer portals, SaaS applications, partner-facing apps, mobile apps, and multi-application ecosystems where users need a consistent identity across services. The platform can integrate with social identity providers and enterprise identity providers depending on the scenario, but provider availability, protocol support, and configuration details should always be validated during design.

Supported application patterns and protocols

Modern CIAM architecture usually includes app registrations, redirect URI configuration, scopes, API permissions, token validation, session settings, and secure client configuration. Microsoft Entra External ID is designed for common application patterns including server-rendered web apps, SPAs, native mobile apps, desktop apps, and protected APIs. Applications should validate tokens correctly, use current Microsoft identity libraries where possible, follow OAuth 2.0 and OpenID Connect best practices, avoid storing secrets in public clients, use PKCE for public clients, and design API authorization around scopes, roles, or claims that your application actually verifies.

Security considerations beyond basic MFA

A secure CIAM deployment is more than a login screen. In 2026, organizations should review MFA requirements, Conditional Access capabilities where licensed and supported, risk-based access options, secure token lifetimes, session management, consent and permissions, app registration hygiene, least-privilege API access, monitoring, audit logs, and incident response. Passwordless and passkey strategies should be considered where they fit the user population and are supported by the selected identity configuration. For regulated industries, tenant location, data residency, retention, privacy, and compliance requirements should be reviewed before implementation.

Do you need to rewrite your applications?

Usually, you do not need to rewrite the entire application, but you should expect development and architecture work. Applications must be able to redirect users to the identity provider, receive authorization responses, validate ID and access tokens, manage sessions securely, request the correct scopes, and enforce authorization in the application and API layer. Microsoft identity libraries can reduce custom code, but configuration, testing, token handling, error handling, and migration planning still require careful implementation.

Typical implementation process

A 2026 implementation typically starts with tenant and architecture planning: deciding whether to use a new external tenant, how applications and APIs will be registered, what identity providers are needed, what sign-up and sign-in flows are required, and how branding, domains, data residency, compliance, and pricing will be handled. The next step is configuration: app registrations, redirect URIs, user flows or equivalent policy configuration, identity provider setup, API scopes and permissions, custom attributes if required, logging, monitoring, and security controls. Finally, applications are updated and tested across web, mobile, SPA, and API scenarios, including token validation, logout behavior, MFA or Conditional Access behavior, error handling, and load or availability requirements.

Migration guidance for existing Azure AD B2C customers

If you already use Azure AD B2C, start with an inventory of tenants, user flows, custom policies, applications, identity providers, custom attributes, API connectors, branding, domains, and user stores. Then compare your current features with Microsoft Entra External ID capabilities and identify gaps, required redesign, migration tooling, user communication, rollback plans, and coexistence needs. Some organizations may keep existing Azure AD B2C workloads in place for a period while building new applications on Entra External ID; others may plan a phased migration. The right path depends on application complexity, custom policy usage, compliance needs, and business risk.

When Microsoft Entra External ID is a good fit

Microsoft Entra External ID is a strong candidate when you need standards-based authentication for customer-facing applications, centralized identity management across multiple apps, integration with Microsoft cloud security and monitoring practices, and a scalable alternative to maintaining your own user database and password system. It may require additional planning if you have highly customized identity journeys, unusual federation requirements, complex legacy apps, or strict data residency and regulatory constraints. Those are design questions to answer before implementation, not after launch.

Key takeaways

• Microsoft Entra External ID is Microsoft’s current CIAM direction for new customer-facing identity projects.
• Azure AD B2C is legacy for new purchases: it became unavailable for purchase by new customers on May 1, 2025, though existing customers can continue operating existing tenants.
• Modern CIAM projects require architecture, app registration, secure token validation, user journey configuration, monitoring, compliance review, and often application code changes.
• Security planning should include MFA, Conditional Access where applicable, token and session controls, least-privilege permissions, app registration hygiene, logging, and privacy requirements.
• Existing Azure AD B2C customers should assess whether to maintain, modernize, or migrate based on application complexity and business risk.

Need help deciding between maintaining Azure AD B2C and moving to Microsoft Entra External ID? IT Partner can assess your CIAM architecture, plan a secure Entra External ID deployment, and support migration through our Microsoft Entra ID, Azure Consulting, Microsoft 365 Security, and Cloud Migration services.