Building Scalable Web Applications

When I first started building web apps, I didn't think much about scale. A single server, a basic database, and some React components were enough. But as projects grew, I learned that architecture decisions made early define how far you can go.

Start With the Data Model

The most impactful decision you'll make is how you model your data. A poorly designed schema will haunt you for the lifetime of the project.

-- Don't do this
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  metadata JSONB -- "we'll figure it out later"
);

-- Do this instead
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  email VARCHAR(255) UNIQUE NOT NULL,
  role VARCHAR(50) NOT NULL DEFAULT 'user',
  created_at TIMESTAMP DEFAULT NOW()
);

Being explicit about your schema forces you to think about your domain upfront.

Caching Is Not Optional

Once your app serves more than a handful of users, you need a caching strategy. I've found a layered approach works best:

1. Browser cache — static assets with long TTLs
2. CDN edge cache — for SSR pages and API responses
3. Application cache — Redis or in-memory for hot data
4. Database query cache — materialized views for expensive aggregations

The Monolith-First Approach

Microservices are tempting, but starting with a well-structured monolith saves months of yak-shaving. You can always extract services later when you have real data about your bottlenecks.

"A distributed system is one where the failure of a computer you didn't even know existed can render your own computer unusable." — Leslie Lamport

Key Takeaways

• Model your data carefully from day one
• Cache aggressively at every layer
• Start monolithic, split when you have evidence
• Measure before you optimize
• Write code that's easy to delete, not easy to extend