Version 1.0 Launched 🚀

Master the Language of Modern Software

The most comprehensive, reliable, and friendly guide for API beginners. From HTTP basics to advanced architectures, we cover it all.

Start Journey Explore Topics
100+ Articles
50+ Interactive Examples
Free Open Source 
GET /api/v1/knowledge HTTP/1.1
Host: learnapi.org
Accept: application/json

# Response
HTTP/1.1 200 OK
Content-Type: application/json

{
  "mission": "Empower developers",
  "topics": [
    "REST", 
    "GraphQL", 
    "gRPC",
    "WebSocket"
  ]
}

Core Curriculum

Structured to help you both consume and build world-class APIs.

Mastering Existing APIs

🚀
01

Get Started

First steps in the world of APIs. Setup and Quickstart.
🌱
02

API Fundamentals

Understanding HTTP, JSON, and the basic building blocks.
🧰
03

Working with APIs

Authentication, environments, and team collaboration.
👻
04

Mocking APIs

Simulate responses to frontend before the backend is ready.

Building Your Own APIs

🎨
05

Designing APIs

REST constraints, resource modeling, and OpenAPI specs.
🛠
06

Developing APIs

Implementation strategies, frameworks, and best practices.
🧪
07

Testing APIs

Automated testing, assertions, and quality assurance.
📝
08

API Documentation

Creating clear, interactive docs for your stakeholders.

Supported Protocols

Deep dives into modern communication standards.

HTTP/REST

The standard for web APIs.

GraphQL

Flexible data queries.

SOAP

Enterprise legacy standards.

WebSocket

Real-time bidirectional.

gRPC

High performance RPC.

SSE

Server-Sent Events.

Common Questions

Quick answers to untangle API concepts.

What is an API?

API stands for Application Programming Interface. It's a set of rules that allows different software applications to communicate with each other.

Read Guide →

How do I read API Docs?

Good documentation explains endpoints, parameters, and authentication. Look for the "curl" examples and response schemas to understand how to interact.

Learn More →

What is SSE?

SSE (Server-Sent Events) allows a server to push real-time updates to a client over a single HTTP connection. It's great for news feeds and tickers.

Explore SSE →

What is OpenAPI Spec?

OpenAPI (formerly Swagger) is a standard for defining REST APIs. It describes endpoints, request/response formats, and auth methods in a machine-readable JSON or YAML file.

View Specification →

How do I call an API?

You can make requests using command-line tools like cURL, UI clients like Apidog or Postman, or code libraries like Axios (JS) and Requests (Python).

See Examples →

How to use AI with APIs?

AI tools can generate OpenAPI specs from natural language, create automated test scenarios, write documentation, and even build mock servers instantly.

AI Workflows →
Live Demo

Experience a Real API

Don't just read about APIs—interact with one. The PetStore API is a comprehensive example demonstrating CRUD operations, authentication, and error handling.

Try PetStore API ↗ 
POST /pet HTTP/1.1
Content-Type: application/json

{
  "name": "doggie",
  "photoUrls": [
    "https://example.com/image.jpg"
  ],
  "status": "available"
}