Edge & APIsEdge Functions
Edge vs Serverless
Two runtimes, different tradeoffs. Pick wrong and you pay for it.
Choose Wisely
Two runtimes, very different tradeoffs. Using edge for database queries or serverless for simple routing decisions costs you money unnecessarily.
The Difference
| Serverless | Edge | |
|---|---|---|
| Runtime | Node.js | Edge (limited) |
| Regions | One (US East) | 30+ globally |
| DB connections | Direct (pooled) | HTTP only |
| Cold start | 200-500ms | 0-50ms |
| Billing | Active CPU time | Per invocation |
Quick Decision
| Your Need | Use |
|---|---|
| Cookie check ("logged in?") | Edge |
| Database query | Serverless |
| Geo redirect | Edge |
| Payment webhook | Serverless |
| A/B routing | Edge |
| PDF generation | Serverless |
Cost Comparison
| Scenario | Edge | Serverless |
|---|---|---|
| Auth token check | $0.50/1M | $2-5/1M |
| A/B routing | $0.50/1M | $3-8/1M |
| DB query | N/A | $1-3/1M |
| Heavy compute | Timeout | $5-20/1M |
When Edge Wins
Routing, cookie checks, bot blocking - anything that reads headers/cookies and makes a quick decision:
export function middleware(request: NextRequest) {
const country = request.geo?.country || 'US';
if (['DE', 'AT', 'CH'].includes(country)) {
return NextResponse.rewrite(new URL('/de' + request.nextUrl.pathname, request.url));
}
return NextResponse.next();
}When Serverless Wins
Database operations benefit from connection pooling:
export async function GET() {
const users = await db.query('SELECT * FROM users');
return Response.json(users);
}With Active CPU pricing, I/O wait time is free. Keep DB work in serverless.
Don't use export const runtime = 'edge' for database routes. HTTP connections from edge = high latency.
See Middleware Patterns for the biggest edge cost trap.