Designing a Unified Single Sign-On Experience Across Shopify and an Existing Application

My client, a digital course provider, was launching a new Shopify storefront while continuing to operate an existing internal application with its own authentication system.

The challenge was to unify user authentication across both platforms so that customers could:

• Sign up once
• Log in once
• Access both the Shopify site and the internal application seamlessly

Security was a top priority, and the client required the use of Azure Active Directory B2C as the sole identity provider, aligning with their existing infrastructure and compliance requirements.

Additional complexity came from Shopify’s authentication constraints, including the need to integrate with Shopify Multipass, manage sessions correctly, and handle re-authentication without degrading user experience.

Before any build work could begin, the client needed absolute clarity on:

• Technical feasibility
• Authentication flows
• Session handling and persistence
• Platform limitations and trade-offs

A dedicated discovery and solution design phase was undertaken to define a robust, scalable SSO architecture before implementation.

The solution focused on:

• Designing Azure B2C as the single source of truth for identity
• Mapping authentication flows between Azure B2C, Shopify (via Multipass), and the internal application
• Defining secure login, signup, and re-authentication processes
• Documenting session handling strategies and where silent authentication was feasible
• Ensuring the solution worked within Shopify’s constraints while remaining future-proof

Clear flow diagrams and documentation were produced to give all stakeholders a shared understanding of how authentication would work end-to-end, reducing implementation risk and preventing costly rework later.

The final output provided a blueprint-ready SSO architecture, enabling the client’s internal team to confidently move forward with implementation as a separate phase.