Architecture Overview

Legacy / Multi-IdP Landscape

The client's ecosystem included multiple platforms each using separate identity systems and legacy IdPs. This fragmented approach created operational complexity, inconsistent user experiences, and duplicated identity logic.

Centralized Identity with Auth0

We introduced Auth0 as the single Identity Provider (IdP) to centralize authentication and provide SSO across the platforms. The new architecture routes authentication through Auth0 while enabling staged coexistence with legacy IdPs during migration.

Migration Strategies (how we moved millions safely)

Lazy Migration (On-Login Migration)

For one product family, we implemented lazy migration: when a user logs in via the new Auth0 flow, the system first validates credentials against the legacy IdP (AWS Cognito). If successful, the user is migrated to Auth0 in real time with no disruption. This minimizes user friction and avoids mass resets.

Bulk Migration with Staged Rollout

For other product users, we ran a bulk migration script to import users into Auth0. To reduce risk, we used A/B testing and staged traffic shifts so a subset of users saw the new login flow early and allowed us to catch issues before full cutover.

Coexistence & Gradual Cutover

During migration, Auth0 and legacy IdPs coexisted. This allowed verification, throttling, rollback, and progressive routing changes to ensure zero downtime and a smooth user experience.

Technology Stack

🔐 Identity & Auth

🧠 Backend & Orchestration

💾 Data & Storage

🧩 Frontend (consumer apps)

Why This Approach

Minimal User Friction

Lazy migration reduces the need for password resets or forced migrations by moving users seamlessly at first successful login. This prioritized user experience and retention.

Controlled Risk with Staged Rollouts

Bulk migration combined with A/B testing allowed us to validate the migration at scale and catch edge cases early, avoiding a risky single cutover.

Single Source of Identity Truth

Consolidating to Auth0 simplifies long-term identity management, improves security posture, and enables consistent SSO across multiple products.

Feature Highlights

Monitoring, Safety & Rollback Measures

Observability & Metrics

We monitored login success rates, error rates, latency, and user drop-offs during migration windows to detect issues in near real time.

Data Integrity & Privacy

All migration flows were designed to preserve password integrity and handle sensitive data securely, following best practices for encrypted transit and storage.

Rollback & Recovery

Rollback plans and staged throttles were prepared to revert traffic to legacy IdPs if critical issues were observed during any migration stage. Automated health checks and canary percentages controlled the pace of rollout.

Challenges & Lessons Learned

If you are planning an IdP consolidation, SSO rollout, or large-scale user migration, we can help design a migration approach that minimizes risk and maximizes user continuity. Reach out and we'll map a migration plan tailored to your systems and user base.