Lessons from keeping a multi-tenant platform at 99.9% uptime

Running a multi-tenant platform teaches you failure modes no tutorial covers.

The notification engine story

Our original notification pipeline processed events synchronously in the request cycle. Under load, API latency climbed with every new tenant. Rebuilding it around Node.js EventEmitters cut API response latency by 27% — and more importantly, decoupled tenant workloads from each other.

What actually matters

1. Isolation by default — a noisy tenant should never be able to slow a quiet one
2. Observability first — Datadog dashboards before features
3. Boring deployments — GitHub Actions, Terraform, no manual steps

More war stories coming.