Case Study · 2025 · Internal R&D · 14 engineering days

Multi-Tenant SaaS Metering Core

Tenant isolation, entitlement, and metering foundation for a B2B SaaS product with per-plan limits.

Reference implementation for our SaaS platform foundation standard.

The problem

SaaS products usually bolt on plans, limits, and tenancy after launch, and then spend the next year fighting the consequences: leaked data across tenants, limits enforced in three inconsistent places, and a pricing change that requires an engineering project.

What we built

Row-level tenant isolation enforced at the database layer with policy tests that fail the build if a query can cross a tenant boundary.
A declarative entitlement model where plans, features, and limits are data, so a pricing change is a configuration change rather than a release.
A metering core recording usage against tenant and feature with soft and hard limit behaviour, plus in-product warnings before enforcement.
Subscription lifecycle wiring to the payment provider with webhook idempotency, proration handling, and reconciliation against provider state.

The result

Cross-tenant access tests passed on all 340 generated policy cases, and introducing a new plan tier required configuration only, with no application code change across the harness.

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