Understanding APIs: API types and custom Endpoint creation

1. Understanding APIs: Types and Custom
Endpoint Creation
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Gideon Yegon
Software Engineer
13/11/2025
1900HRS

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API = Application Programming Interface
What is an API?
It’s a bridge that allows two applications to communicate.
Example:
●When you log in with Google Your app uses Google’s API
→
to authenticate you.
Visual: Diagram showing two apps talking via an API.
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What is an API?
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Frontend
Server
API

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Why APIs Matter
● Enable integration between systems
● Encourage reusability of code
● Support automation and scalability
●Power modern apps: mobile, web, IoT, AI, etc.
Example:
Uber uses APIs for maps, payments, and messaging.

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Name an API you have interacted with

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Types of APIs
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Type Description Example
RESTful Uses HTTP and resources (URLs). GET /users
GraphQL Query language for APIs; fetch only what
you need.
{ user { name,
email } }
SOAP XML-based; strict protocol. <soap:Envelope>
WebSocket Real-time communication. Chat apps
gRPC Uses Protocol Buffers for fast
communication.
Microservices

8. RESTful APIs – The Standard
Core Ideas:
●Stateless communication
● Uses HTTP methods
●Returns data (usually JSON)
●Resource-based URLs
GET https://api.example.com/users
POST https://api.example.com/users
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HTTP Methods
Method Action Example
GET Retrieve data /users
POST Create new data /users
PUT Update existing data /users/1
DELETE Remove data /users/1

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HTTP Status Codes
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Code Meaning Example
200 OK – Request successful ✅
201 Created – New resource made 🆕
400 Bad Request – Invalid input ⚠️
401 Unauthorized – Need credentials 🔒
404 Not Found – Resource missing ❓
500 Server Error – API issue 💥

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Postman – Your API Playground
Postman lets you:
●Send and test HTTP requests
●Automate tests and collections
●Document your APIs
●Simulate environments

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Demo

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●https://jsonplaceholder.typicode.com/posts
●https://library-api.postmanlabs.com/books

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Create an endpoint for your app
Example scenario: Student registration system
POST /api/students Add student
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GET /api/students Get all students
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GET /api/students/{id} Get specific student
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PUT /api/students/{id} Update student info
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DELETE /api/students/{id} Remove student
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Building a Custom API Endpoint

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●Use clear, descriptive endpoints
●Return consistent JSON responses
●Include proper status codes
●Document your API
(Swagger / Postman Docs)
●Version your API: /api/v1/
Tips for Designing Good APIs

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GraphQL vs REST
Feature REST GraphQL
Data Fetching Multiple endpoints Single endpoint
Response Size Fixed Flexible
Caching Simple Complex
Use Case Simpler apps Dynamic queries

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●https://restfulapi.net/
●https://graphql.org/learn/
●https://developer.mozilla.org/en-US/docs/Web/HT
TP/Methods
●https://learning.postman.com/
●https://nodejs.org/docs/latest/api/
Tips for Designing Good APIs

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Contact Details
Phone :
yegon@datany.online
254712 269 086
Nairobi, Kenya
Address :
Email :
Thank
you
https://gideonyegon.vercel.app