📝 AWS API Gateway — Full Blog (Part 1)

3 min readSep 1, 2025

1. Introduction

When you use apps like Swiggy, Zomato, Ola, Uber, or Paytm, have you ever thought about how these apps connect to their backend servers?

For example:

You open Zomato → search for “Pizza”.
The app shows you a list of restaurants.
You place an order → payment happens → delivery tracking starts.

Behind the scenes, all this happens because of something called APIs.

What is an API?

API stands for Application Programming Interface.

In simple words:

API is like a messenger between two systems.
It takes your request, tells the server what you need, and brings back the response.

👉 Real-life example:
Think of a restaurant waiter.

You (the customer) ask for food → that’s the request.
The waiter takes your order to the kitchen (server).
The kitchen prepares the food and gives it back to the waiter.
The waiter serves it to you → that’s the response.

Here:

You = Client (like your mobile app)
Kitchen = Server (where the business logic is running)
Waiter = API

This is exactly how apps talk to servers.

What is an API Gateway?

Now imagine a big hotel with 20+ different kitchens — Indian, Chinese, Italian, Dessert, Beverages.
If customers directly run to the kitchens, it will create chaos.

So the hotel keeps one reception desk (gateway).

You place your order at reception.
Reception decides which kitchen to send your order to.
Then it brings back the food.

This reception desk is like an API Gateway.

👉 Definition:
API Gateway is a service that acts as a front door for your applications (mobile apps, web apps, etc.) to access data, business logic, or backend services.

It manages:

Who can enter (security)
How many people can enter at a time (rate limiting)
Where to send requests (routing)
And keeps logs of everything(cloudwatch)

Why AWS API Gateway?

There are many API Gateways (Kong, Apigee, etc.), but AWS API Gateway is fully managed and deeply integrated with AWS services like Lambda, DynamoDB, EC2, S3.

It is serverless, meaning:

You don’t manage any servers
You pay only when someone uses your API
It automatically scales from 1 request per day to millions per second

That’s why it is very popular for startups, enterprises, and even personal projects.

2. Why do we need AWS API Gateway?

Let’s take a simple example.

Imagine you are building an Online Shopping App.

Mobile app → sends requests like Get Product List, Add to Cart, Make Payment.
Backend → multiple services: product service, order service, payment service.

Problem without API Gateway:

Your mobile app has to directly talk to each backend service.
You must manage authentication for each service separately.
Each service might have a different endpoint.
You will face issues in scaling, throttling, and monitoring.

This becomes very complex very fast.

Solution with API Gateway:

Your mobile app talks only to one endpoint (API Gateway).
API Gateway then routes the request to the correct backend service.
It manages authentication, throttling, caching, and logging for you.

👉 Think of it like Swiggy delivery partner.

Customer places an order on Swiggy app.Swiggy assigns a delivery person.
That delivery person coordinates with restaurant, pickup, and drop.
Customer only interacts with Swiggy → not directly with the restaurant.

This is exactly what API Gateway does.

Next part →Core Concepts of AWS API Gateway (Endpoints, Methods, Resources, Stages, Integrations, etc.) with real-life examples.