Amazon API Gateway is a fully managed service that lets you:

✅ Create

✅ Publish

✅ Secure

✅ Monitor

✅ Scale

...REST, HTTP, and WebSocket APIs—without managing any servers.

Think of it as the gatekeeper between your frontend (clients) and backend (Lambdas, EC2, DynamoDB, etc.).

⚙️ How It Works (Simple Flow) 

[User / Client]  
     ↓  
 [API Gateway] ← rate limits, security, validation  
     ↓  
[Backend] → Lambda / EC2 / DynamoDB / S3 / etc.  
     ↓  
[API Gateway]  
     ↓  
[Client gets response]

You define routes (GET /products, POST /order), and API Gateway handles:

  • Traffic management
  • Throttling
  • Security (Auth, WAF, CORS)
  • Request/Response transformations

🧩 Types of APIs in API Gateway

Type Use Case Backend Real-life Example
REST API Classic RESTful APIs Lambda, EC2, etc. Mobile app backend
HTTP API Lightweight, low-cost APIs Lambda, ALB, etc. Internal microservices
WebSocket API Real-time, two-way comms Lambda, EC2 Chat app, Live feeds

1. REST APIs (Legacy but Feature-Rich)

Supports:

  • Custom authorizers
  • Request/response transformation
  • API keys, usage plans
  • Fine-grained throttling
  • Stage variables & caching

Best for: Complex APIs needing caching, transformations, or advanced auth.

⚠️ Slightly more expensive than HTTP API.

2. HTTP APIs (Modern, Fast, Cheaper)

Newer, leaner, simpler alternative to REST API.

Supports:

  • OAuth2, JWT authorizers
  • Direct Lambda, ALB, Step Functions integration
  • Lower latency, lower cost

Ideal for most modern apps (unless you need legacy REST API features).

3. WebSocket APIs (Real-time Communication)

Use case: 2-way communication between client and server.

Perfect for:

  • Chat apps 💬
  • Live dashboards 📈
  • Online games 🎮
  • IoT device messaging 🔌

How it works:

  • Clients connect & stay connected
  • Backend responds via Lambda or other services
  • Define $connect, $disconnect, and $default routes

Key Features of API Gateway

Security

  • IAM authorization
  • Cognito authentication
  • Custom Lambda authorizers
  • API keys
  • WAF integration (block attacks!)

Transformations

  • Modify requests/responses using Mapping Templates (VTL)
  • Useful for legacy backends or non-JSON APIs

Throttling & Quotas

  • Protects backend from overuse/abuse
  • Define limits per API key / stage / method

Monetization (Usage Plans)

  • Sell API access with API keys + usage plans
  • Charge per request

Monitoring (CloudWatch)

  • Track request counts, latency, errors
  • Create alarms & dashboards

Authentication Options

Auth Type Best For
IAM Internal AWS calls
Cognito User-facing apps
Lambda Authorizer Custom logic (token validation)
JWT/OAuth2 (HTTP API) Modern auth (Okta, Auth0)

Real-World Use Cases

Project API Type Backend
Mobile backend HTTP API Lambda
Serverless web app HTTP API Lambda + DynamoDB
Admin dashboard REST API EC2 + RDS
Live chat app WebSocket API Lambda
IoT telemetry WebSocket API Kinesis / Lambda
SaaS with user roles REST API Lambda + Cognito

When to Use Which?

Need Use This
Basic API, lowest cost HTTP API
Full control, caching, keys REST API
Real-time 2-way messaging WebSocket API

TL;DR Comparison

Feature REST API HTTP API WebSocket API
Speed ⚠️ Moderate ⚡ Faster ⚡ Real-time
Cost 💰 Higher 💸 Cheaper ⚡ Depends
Use Case Complex apps Simple APIs Realtime comms
Caching ✅ Yes ❌ No ❌ No
Auth All methods JWT, IAM IAM

Final Thoughts

  • HTTP API → Best for most modern apps (cheaper, faster).
  • REST API → Needed for advanced features (caching, transformations).
  • WebSocket API → Essential for real-time apps (chat, live updates).

API Gateway simplifies API management, letting you focus on business logic instead of infrastructure.

🔹 Got questions? Drop them in the comments! 👇