How To Create An API? (10 Tutorials)

Behind almost every successful web application, there is an easy-to-use & feature-rich API as they simply help the main application to spread into others & reached by more users.

Also, an API-enabled application can be easily developed further using the API itself.

In order to create an API for your web application, here are 10 tutorials to get you started. But before that, you may want to checkout the video: How To Design A Good API and Why it Matters by Google.


PHP
Create a REST API with PHP

Create REST API With PHP

A very detailed yet easy-to-implement tutorial on creating a REST API with PHP.

And, there is a follow-up article: "Making RESTful Requests in PHP" by the same author which can guide you as well.
How to Add an API to your Web Service (PHP)

Create API PHP

A detailed tutorial which describes the concepts like REST, SOAP & creates an API step-by-step with PHP.

Implement a Rest API with the Zend Framework

API With Zend

This example utilizes controllers in an MVC style application. Most of the stuff is handled by an instance of Zend_Rest_Server so it shows implementing to our service.
Creating a Simple REST API With VB, PHP and MySQL

REST API With PHP,MySQL & VBScript

This article covers both creating an API with PHP where the data is stored in a MySQL database & reaching to the API with a VBScript file.
Create Your Own Custom API (PHP)

Create A Custom API

The tutorial describes a PHP API returning XML data in 6 steps:

* Create Your Own Custom API
* Developing the basic API layout
* The Client
* The Server
* The Server Class
* The "Test" Step

Towards RESTful PHP – 5 Basic Tips

PHP API Tips

Ok, this is not a tutorial but includes very handy tips that can be used when creating a REST API with PHP for the security & ease of usage of the API.


Rails
Creating Open Web APIs: Exploring REST and WOA in Rails 2.0

Creating Open Web APIs

As Rails automatically offers URL addressable resources for all the data in a Rails web application, every Rails application already has a ready-to-go RESTful API". The tutorial explains how to use it in detail.
How to Make an API for a Rails App?

Creating An API For Rails Application

The article describes the 2 options for creating an API:

* HTTP Basic Auth
* Using API key

and provides example codes o get you started.
Putting REST on Rails

Ruby on Rails And Rest

The tutorial uses the RESTful Rails Controller & creates a simple RESTful Rails application with a full test suite and HTTP method dispatching.


ASP.NET
Create REST API using ASP.NET MVC (JSON & XML)

Create API With Asp.Net

A solid start to creating your own REST API with ASP.NET MVC.

Considering, depending on the type of the request you may want to sendXML or JSON data, the tutorial provides a class which can return both.