Multi-Tenant SaaS Application
A resourcing and project management platform for HorizonFlow, rebuilt on proper multi-tenant architecture to support their growth.
Customer: HorizonFlow (demo)
HorizonFlow's original product was architected for a single large customer and needed a fundamental redesign to serve many client organizations securely and independently as they moved toward a broader SaaS model.
Challenge
HorizonFlow's existing system used a shared-schema model with organization IDs scattered inconsistently across tables — workable for one customer, but risky and hard to reason about as they onboarded additional client organizations with strict data separation expectations.
Solution
We redesigned the data architecture around a consistent, enforced tenancy model, migrated existing data into the new structure, and rebuilt the permission system to support organization-level and role-level access control cleanly. The migration was executed incrementally against the live system rather than as a single cutover.
Architecture
The platform uses PostgreSQL row-level security to enforce tenant isolation at the database layer, rather than relying solely on application-level filtering — reducing the risk of a query bug ever leaking data across tenants. Authentication and authorization are centralized in a shared middleware layer used consistently across all API routes, replacing the ad hoc checks scattered through the original codebase.
Key features
Database-enforced tenant isolation
Row-level security prevents cross-tenant data leaks at the database layer, not just in application code.
Centralized authorization
A single, consistently applied permission layer replaces scattered ad hoc checks.
Incremental migration
Existing customer data migrated without a disruptive full cutover.
Organization-level administration
Client organizations can manage their own users and permissions independently.
Integrations
Existing customer data
Migrated incrementally from the prior single-tenant data model.
SSO providers
Organization-level single sign-on for enterprise client organizations.
Representative outcomes
Enforced data isolation
Tenant separation is guaranteed at the database layer, not dependent on application code being correct every time.
Faster onboarding of new organizations
New client organizations can be provisioned without custom engineering work.
Reduced permission-related bugs
Centralized authorization eliminated a class of bugs from inconsistent per-route checks.
Technologies
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