Horizontal vs. Vertical Scaling
Understand the two fundamental ways to add capacity to an API — scaling up versus scaling out — and how to choose between them based on cost, limits, and architecture.
Two Ways to Grow
When an API runs out of capacity you have two levers:
- Vertical scaling (scale up) — make the machine bigger
- Horizontal scaling (scale out) — add more machines
Each has very different cost and reliability profiles.
Vertical Scaling Explained
Vertical scaling means upgrading a single server: more CPU cores, more RAM, faster disks.
It is simple — no code changes — but you eventually hit the largest instance available, and that one box is a single point of failure.
All lessons in this course
- Understanding API Scalability
- Key Scalability Metrics
- Stateless vs. Stateful API Design
- Horizontal vs. Vertical Scaling