What is a RESTful API?

Elliot Forbes ⏰ 3 Minutes 📅 Apr 15, 2017

As a developer I spend a lot of time developing new or improving on existing RESTful APIs and one of the big questions I’ve been asked is - What is a REST API?

This tutorial will try to explain in layman’s terms what a REST API is and how we can utilize these APIs in order to build our own systems.

REST Basics

REST - Representational State Transfer.

API - Application Programming Interface

Most, if not all, large popular websites will rely upon some form of REST API in order to deliver some content or functionality to their users. Some sites like Facebook and Twitter actually expose some of these APIs to outside developers to build their own tools and systems.

We can communicate with REST APIs using HTTP requests, much like you’d do to navigate to a website or load an image. We can do HTTP requests to certain API urls and these urls would then return the information we required, or we could push data to an API url in order to change some data in a database.

Typically we send HTTP requests to an URL that we have defined in our REST API and it would either perform a given task for us or return a certain bit of data. Most APIs these days would return a response to us in the form of JSON.


A Simple Example

Imagine you wrote a bit of code that gives you the current weather conditions at your house. It reads the temperature, humidity and rainfall and stores them locally. How would we then expose this information in such a way that websites or other applications could view it?

One answer to this question is by wrapping it in a RESTful API.

We could expose our code and wrap it in an API so that whenever we navigated to say http://localhost:8000/api/weatherStats it would give us a JSON response that contained all the current weather stats.

Why Do We Do This?

Improved Code Reuse - By exposing our code through REST APIs we essentially give ourselves a greater degree of flexibility. We can develop our software once and should we wish to use the same code again in a different project it would be easy, we could simply send HTTP requests to our API and we’ve reduced the need to duplicate our work efforts.

Always Available - REST APIs are typically things that are running and available all the time. We make them very stable and as a result we can interact with them wherever we are in the world as long as we have internet connectivity.

Taking it Further

If you want to learn how to implement your own REST APIs then I suggest you have a look at my tutorial on Writing RESTful APIs in Go

Further Reading:

If you enjoyed this article then you may also enjoy some of my other articles on the site: