The Breaking Point

Our Node.js API was handling 5,000 requests per second (RPS) just fine—until one day, it wasn’t.

• Latency spiked from 50ms to 2+ seconds
• Database connections maxed out
• Deployments took 15+ minutes

The culprit? A monolithic architecture that couldn’t scale.

After a painful rewrite, we learned why monoliths crumble under pressure—and how to avoid the same fate.

1. The 5 Reasons Monolithic Node.js Apps Fail

🚨 Problem #1: The Database Bottleneck

• Single database = Contention under high load
• No read/write separation = Queries block each other

Example:

// Monolith: All services hit the same DB
app.post('/orders', () => db.query('INSERT...'));
app.get('/analytics', () => db.query('SELECT...')); // Blocks writes!

🚨 Problem #2: Uncontrolled Dependency Bloat

• Giant node_modules (500MB+ is common)
• One broken dependency = Entire app crashes

🚨 Problem #3: Inefficient Scaling

• Vertical scaling only (bigger servers, not more servers)
• No isolation = A bug in one feature takes down everything

🚨 Problem #4: Slow Deployments

• 15-minute CI/CD pipelines (testing the whole monolith)
• Riskier releases (can’t deploy features independently)

🚨 Problem #5: Team Collisions

• 10+ developers constantly merging into one codebase
• Merge hell = "Who broke the tests?!"

2. How We Fixed It: The Microservices Transition

Step 1: Decoupled the Database

• Orders DB (PostgreSQL)
• Analytics DB (TimescaleDB)
• Caching layer (Redis)

Step 2: Split the Monolith

Before:
monolith/
  ├── orders.js
  ├── analytics.js
  └── auth.js

After:
services/
  ├── orders/ (Fastify + PostgreSQL)
  ├── analytics/ (h3 + TimescaleDB)
  └── auth/ (Express + Redis)

Step 3: Adopted Kubernetes

• Auto-scaling per service (not the whole app)
• Isolated failures (orders down ≠ auth down)

Results:

✔ Latency dropped back to 60ms at 10K RPS
✔ Deployments now take <2 minutes
✔ Teams deploy independently

3. When to Stick with a Monolith

✅ Early-stage startups (speed > scale)
✅ Simple apps (CRUD APIs with low traffic)
✅ Small teams (1-3 devs)

Key Takeaways

🔹 Monoliths fail when:

• Traffic grows
• Teams expand
• Databases choke

🔹 Microservices help when:

• You need independent scaling
• Teams own features end-to-end
• Zero-downtime deploys matter

🔹 But don’t over-engineer! Start monolithic, split only when needed.

Have you hit scaling walls with Node.js? How did you solve it?

Further Reading

• Node.js Microservices Guide
• When to Split a Monolith