Key Topics to Learn API Development

A roadmap that can make things easy...

In today’s software development world, APIs are everywhere. Whether you’re building a web application, a mobile app, or even a smart device, chances are you’ll be working with APIs.

So, if you’re a developer (or aspiring to be one), learning API development is a crucial skill.

But where do you start? What should you learn first? What tools do you need?

Let’s break it all down into a topic map so you can build a strong foundation in API development.

1 - Start with API Fundamentals

Before diving into code, you need to understand what an API actually is. API stands for Application Programming Interface, which is a set of rules that allow one piece of software to communicate with another.

Types of APIs:

• REST (Representational State Transfer): The most common type. Uses standard HTTP methods.

• SOAP (Simple Object Access Protocol): XML-based and used in older systems.

• GraphQL: Allows clients to request exactly the data they need.

• gRPC: A high-performance, contract-based API framework by Google.

You can play around with the diagram on Eraser.io

Also, learn the difference between API vs SDK. An SDK (Software Development Kit) often contains APIs along with tools, documentation, and utilities to help you work with a platform.

2 - Understand Requests and Responses

APIs communicate over the web, so understanding HTTP is essential.

• HTTP Methods:

  • GET: Fetch data.

  • POST: Create a new resource.

  • PUT: Update an existing resource.

  • DELETE: Remove a resource.

  • PATCH: Partial update.

• HTTP Status Codes:

  • 200 OK: Successful request.

  • 201 Created: Resource created.

  • 400 Bad Request: Client-side error.

  • 401 Unauthorized: Authentication needed.

  • 404 Not Found: Resource doesn't exist.

  • 500 Internal Server Error: Server-side problem.

• Headers: Include extra info like content type, authentication tokens, etc.

Learning how to read and send HTTP requests/responses is the backbone of working with APIs.

You can play around with the diagram on Eraser.io

3 - Learn About Authentication and Security

Most real-world APIs are not public—you need permission to use them. This is where authentication and security come in.

Common mechanisms:

• API Keys: Simple token-based access.

• Basic Auth: Username and password in headers (not secure without HTTPS).

• OAuth 2.0: Used for secure delegated access (e.g., signing in with Google).

• JWT (JSON Web Tokens): Secure, stateless tokens for managing sessions.

You can play around with the diagram on Eraser.io

In addition, you’ll want to understand:

• HTTPS vs HTTP

• Rate limiting

• CORS (Cross-Origin Resource Sharing)

• Input validation to prevent injection attacks

Security is non-negotiable in production systems.

4 - API Design and Development

Good APIs are easy to use, predictable, and consistent. When designing APIs, follow RESTful principles:

• Use resource-based URLs like /users/123/orders.

• Use appropriate HTTP methods.

• Keep APIs stateless—each request should contain everything the server needs.

• Add versioning to prevent breaking existing clients: /v1/users.

• Implement pagination for large lists: /users?page=2&limit=50.

Also, use tools to make development smoother:

• OpenAPI (Swagger): Design and document APIs in a machine-readable format.

• Postman: Test and explore APIs.

• Insomnia: A popular alternative to Postman.

A well-designed API improves both developer experience and long-term maintainability.

5 - Learn API Testing

Before deploying an API, you need to test it thoroughly.

Testing Tools:

• Postman: Send requests, verify responses, and create test suites.

• cURL: Command-line tool for quick testing.

• SoapUI: Great for testing SOAP and REST APIs.

• Newman: CLI tool to run Postman collections in CI/CD pipelines.

You should test for:

• Correct status codes

• Data accuracy

• Authentication flow

• Error handling

• Performance and rate limits

Don’t skip this step. Testing is what turns code into a reliable service.

6 - Understand API Deployment and Integration

Once your API is built and tested, it’s time to deploy it and connect it with other systems.

• Learn how to deploy your API using cloud platforms like AWS, Azure, or Heroku.

• Get familiar with API Gateways like:

  • AWS API Gateway

  • Kong

  • Apigee

These gateways help with routing, authentication, rate limiting, caching, and more.

You can play around with the diagram on Eraser.io

Lastly, learn to consume APIs in various programming languages:

• JavaScript: Using fetch() or Axios.

• Python: Using requests library.

• Java: Using libraries like Retrofit or RestTemplate.

Also, experiment with public APIs like:

• Google Maps

• Stripe (payments)

• Spotify

• OpenWeather

Practicing with real APIs helps you understand real-world edge cases and integrations.

So, what else will you add to learn about APIs?

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Shoutout

Here are some interesting articles that I read this week:

• Range Queries by

  Franco Fernando

• Don't get left behind. The software engineering trends you absolutely need to know by

  Fran Soto

• Dead Letter Queues Are Not Your Safety Net by

  Raul Junco

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That’s it for today! ☀️

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