SPA vs MPA: When to Use Which

The fundamental architectural decision in web development is whether to build a Single-Page Application (SPA) or a Multi-Page Application (MPA).

Single-Page Application (SPA)

In an SPA, the browser loads a single HTML page and then dynamically updates the content using JavaScript. Navigation between "pages" is handled client-side — no full page reloads.

Examples

• React apps with client-side routing (react-router)
• Angular apps (@angular/router)
• Vue apps (vue-router)

Pros

• Fast navigation: Only data changes, not the whole page
• Rich interactivity: Complex client-side logic, animations
• Shared state: JavaScript state persists across "pages"
• Offline support: Can cache data and work without a server

Cons

• Large initial bundle: All JavaScript must download before the app works
• SEO challenges: Search engines struggle with client-rendered content
• Memory leaks: State accumulates in the browser tab
• Slow Time to First Byte (TTFB): Server just sends a shell, not real content

Multi-Page Application (MPA)

In an MPA, every URL maps to a server-rendered HTML page. Navigating between pages causes a full page load.

Examples

• Traditional server-rendered apps (Rails, Django, Laravel)
• Modern SSR/SSG: Next.js with SSR/SSG, Nuxt.js with SSR/SSG

Pros

• Instant rendering: Server sends complete HTML on first load
• Better SEO: Search engines see real content
• Lower memory usage: Browser doesn't hold state between pages
• Smaller bundles: Only the JS for the current page loads

Cons

• Full page reloads: Slower navigation, lost state
• More server work: Each page requires server rendering
• Limited interactivity: Complex client-side logic is harder

Modern Hybrid Approaches

Server-Side Rendering (SSR)

The server generates the full HTML on each request, then the client takes over for interactivity.

Next.js: getServerSideProps — renders on every request Nuxt.js: asyncData — renders on every request

Tradeoff: Fast initial load + SEO, but server must render every page.

Static Site Generation (SSG)

The server generates HTML at build time, not at request time.

Next.js: getStaticProps — generates at build time Nuxt.js: generate — pre-renders all pages

Tradeoff: Blazing fast initial load + can be CDN'd, but content must be known at build time.

Incremental Static Regeneration (ISR)

Static pages that can be updated in the background after build.

Next.js: revalidate option in getStaticProps

Tradeoff: Static performance + dynamic updates, but with eventual consistency.

Decision Matrix

The Rendering Triangle

You can pick any two:

• ✅ Fast initial load
• ✅ Search engine friendly
• ✅ Rich interactivity

SPA gives you #1 and #3 (not #2). MPA gives you #1 and #2 (not #3). SSR/SSG gives you #2 and #3 (slower than SSG).