Edge computing brings computation closer to users—running code at CDN edge locations worldwide rather than centralized data centers. This fundamental shift enables new performance and personalization capabilities for web applications.
What Is Edge Computing?#
Traditional Architecture#
User (Tokyo) → CDN (static) → Origin Server (US-East) → Response
└── 200ms latency
Edge Architecture#
User (Tokyo) → Edge Function (Tokyo) → Response
└── 20ms latency
Edge functions run at hundreds of locations globally, processing requests milliseconds from users.
Edge Platforms#
Major Providers#
Cloudflare Workers
- V8 isolates
- 0ms cold start
- 200+ locations
Vercel Edge Functions
- Built on Cloudflare
- Next.js integration
- Edge middleware
AWS Lambda@Edge / CloudFront Functions
- CloudFront integration
- Regional edge caches
- Origin request/response
Deno Deploy
- Deno runtime
- TypeScript native
- Global deployment
Edge Function Basics#
Cloudflare Workers#
Vercel Edge Functions#
Common Use Cases#
Geolocation and Personalization#
A/B Testing#
Authentication at the Edge#
Rate Limiting#
Edge Middleware#
Next.js Middleware#
Data at the Edge#
Key-Value Storage#
Durable Objects (Stateful Edge)#
Limitations and Trade-offs#
Edge Constraints#
Limited capabilities:
- No filesystem access
- Limited CPU time (50ms - 30s depending on plan)
- Memory limits (128MB - 512MB)
- No persistent connections to databases
- Limited Node.js API compatibility
Solutions:
- Use edge-compatible libraries
- Cache database results in KV
- Use edge-native databases (PlanetScale, Turso)
- Fallback to regional functions for complex operations
When NOT to Use Edge#
Keep at origin:
- Complex database queries
- Long-running operations
- Heavy computation
- Large file processing
- Operations requiring full Node.js API
Use edge for:
- Routing and redirects
- Authentication checks
- Personalization
- A/B testing
- Static asset optimization
- Simple API responses
Hybrid Architecture#
┌─────────────────────────────────────────────┐
│ User │
└─────────────────────┬───────────────────────┘
│
┌─────────────────────▼───────────────────────┐
│ Edge Function │
│ - Auth check │
│ - Geo-personalization │
│ - Route decision │
└─────────────┬───────────────┬───────────────┘
│ │
┌─────────▼─────────┐ ┌───▼────────────────┐
│ Static Assets │ │ Origin Server │
│ (CDN Cache) │ │ (Complex Logic) │
└──────────────────┘ └────────────────────┘
Deployment#
Cloudflare Workers#
Vercel Edge#
Conclusion#
Edge computing fundamentally changes web architecture—moving computation from centralized origins to distributed edge locations milliseconds from users. This enables personalization, security, and performance improvements impossible with traditional architectures.
Start with simple use cases: authentication, redirects, or personalization. As you gain experience, expand to more complex edge logic. The future of web development is increasingly at the edge.