How API Gateway Works (Simple Explanation)
What is an API Gateway?
An API Gateway is a single entry point that receives all client requests and routes them to the appropriate backend services while handling security, traffic control, and monitoring.
In modern microservices architecture, clients never communicate directly with backend services. Instead, all requests pass through the API Gateway.
This approach improves security, scalability, and system control.
👉 How to Code an API Gateway (Cloud Native) using CloudFlare
https://youtu.be/D4Lt18qYkjc
How API Gateway Works
An API Gateway sits between the client and backend services and processes every request in the following steps:
- Receives the incoming request from client (web, mobile, or frontend)
- Authenticates and validates the request
- Applies rate limiting and throttling
- Routes the request to the correct backend service
- Collects logs, metrics, and traces
- Sends the response back to the client
This entire process happens within milliseconds.
API Gateway Request Flow
Client
↓
API Gateway
↓
Authentication
↓
Rate Limiting
↓
Routing
↓
Backend Services
↓
Response
Why API Gateway is Important
Without an API Gateway, clients must communicate directly with multiple backend services, which creates several problems.
Problems without API Gateway:
- Complex frontend logic
- Security exposed at multiple points
- Difficult authentication handling
- No centralized monitoring
- Hard to scale independently
With API Gateway:
- Single secure entry point
- Centralized authentication
- Traffic control and rate limiting
- Better observability
- Easier microservice scaling
Core Responsibilities of an API Gateway
1. Authentication & Authorization
The gateway verifies tokens (JWT, OAuth, API keys) before forwarding requests.
2. Routing
Requests are routed to correct services based on path, method, or headers.
Example:
- /users → User Service
- /orders → Order Service
3. Rate Limiting
Prevents abuse by limiting how many requests a client can make per second.
4. Load Balancing
Distributes traffic across multiple backend instances.
5. Observability
Collects logs, metrics, and distributed traces.
This is critical for production systems.
API Gateway in Microservices Architecture
In microservices, each service is deployed independently.
API Gateway acts as:
- A boundary
- A security layer
- A traffic controller
It protects backend services from direct exposure to the internet.
Common API Gateway Examples
- Cloudflare Workers (Edge-based)
- Kong
- NGINX
- AWS API Gateway
- Apigee
- Traefik
Each tool differs in performance, cost, and architecture.
Edge API Gateway vs Traditional Gateway
Traditional API Gateway
- Runs in centralized servers
- Higher latency
- Regional deployments
Edge API Gateway
- Runs close to users
- Ultra-low latency
- Global availability
Cloudflare Workers is a strong example of edge-based API Gateway.
When Should You Use an API Gateway?
You should use an API Gateway when:
- You have multiple backend services
- You need centralized security
- You want traffic control
- You want observability
- You are building scalable systems
For simple monolithic apps, an API Gateway may not be necessary.
Real-World Example
A frontend application sends a request:
GET /api/orders
The API Gateway:
- Validates user token
- Checks rate limit
- Routes request to Order Service
- Logs request metrics
- Returns response
Frontend never interacts directly with backend services.
Watch Full Practical Implementation
Complete hands-on tutorial available on the CodingMavrick YouTube channel.
In the video, we cover:
- Building API Gateway using Cloudflare Workers
- Routing logic
- Authentication
- Rate limiting
- Observability integration
- Production deployment
Related Topics
- Microservices Architecture
- Cloudflare Workers
- Distributed Tracing
- Observability
- CI/CD Pipelines
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