API Key Authentication
Next.js API Routes
Protect App Router and Pages Router API routes
Express Middleware
Reusable auth middleware for Express apps
FastAPI Dependencies
Dependency injection pattern for FastAPI
Flask Authentication
Decorator-based auth for Flask applications
Go Standard Library
Production-ready net/http middleware
Go Gin Framework
Middleware for Gin web framework
Go Echo Framework
Middleware for Echo web framework
Cloudflare Workers
Edge-first API authentication
Rate Limiting
Per-User Rate Limits
Different limits based on user tier
Endpoint-Specific Limits
Tighter limits on expensive operations
FastAPI Rate Limiting
Implement rate limiting in FastAPI
Usage & Billing
Usage-Based Billing
Track and bill based on API usage
Tiered Subscriptions
Free, Pro, Enterprise with different limits