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Posted November 4, 2022

What Is a RESTful API?

Learn why most web apps and web services use REST (RESTful) APIs.


Most web traffic today is actually API traffic for web applications and REST web services. Many times, when you use a social media app, a banking app, look up a product on an e-commerce site, or watch an auto-play list of short videos, the apps you’re using are making API calls that websites, apps, and operating systems (OS) can orchestrate into intelligent functions such as biometric security and complying with local privacy regulations that we now take for granted. Keep reading to learn why most web apps and web services use REST (RESTful) APIs–and why GraphQL and gRPC APIs are emerging as alternatives to REST APIs in a growing number of organizations.

What is an API?

API stands for Application Programming Interface. APIs allow endpoints (such as mobile devices and databases maintained on web servers) to integrate with each other in accordance with business logic that developers build into the API. There are many different types of APIs, but typically when you hear people talk about APIs (Google API, Twitter API, etc.) they are talking about a RESTful API for public consumption. REST APIs may also be internal or private for internal apps and/or internal cloud infrastructure.

What is a RESTful API?

REST stands for REpresentational State Transfer. This refers to a style of web architecture that has many underlying characteristics and governs the behavior of clients and servers. REST is defined by 6 constraints: client-server, stateless. Cacheable, Layered system, Uniform Interface, Code on Demand (optional).

This kind of API works like a website – you send your request to a server via HTTP and you will get a website in response.

A REST API defines a set of functions which developers can perform requests and receive responses via HTTP protocol such as GET, DELETE, and POST.

If an API follows the REST “rules,” it can be called a RESTful API. Thanks to this interface, resources can be called upon singularly. With this feature, one of fastest growing use cases for REST APIs involves connecting microservices in data maps that allow microservices to work together like a traditional monolithic application. This setup makes it possible for mobile apps that are built from microservices to continue providing expected functionality to users while select components (or microservices “concerns”) are being edited or improved.

Today’s apps and games that provide top customer experience (CX) employ short release cycles and microservices powered by REST APIs to maintain high levels of code reliability, resilience and efficiency throughout iterative changes. 

RESTful API Example

We all know what a Facebook page looks like.

What if we change the “www” in the URL bar to the Facebook API using “graph?”

You will get some code that might be nonsense, but it is actually structured data, like an Excel spreadsheet would be, but the difference is that it could be XML or JSON.

In Excel, you can ask what the key value in Cell A6 is and look at it.

With RESTful every resource has a key value, called e.g. JSON array, and you can ask for key values singularly. In the case of a Facebook page, you could ask for the data under the key “likes” to find out how many likes a page has.

Here is another example with Google Maps:

So we are asking for:

Server =

Resource =





Request = ?address=Chicago

So our whole URL would look like this:

We will get the following information back:

{ "results": [ { "address_components": [ { "long_name": "Chicago", "short_name": "Chicago", "types": [ "locality", "political" ] }, { "long_name": "Cook County", "short_name": "Cook County", "types": [ "administrative_area_level_2", "political" ] }, { "long_name": "Illinois", "short_name": "IL", "types": [ "administrative_area_level_1", "political" ] }, { "long_name": "USA", "short_name": "US", "types": [ "country", "political" ] } ], "formatted_address": "Chicago, Illinois, USA", "geometry": { "bounds": { "northeast": { "lat": 42.023131, "lng": -87.52366099999999 }, "southwest": { "lat": 41.6443349, "lng": -87.9402669 } }, "location": { "lat": 41.8781136, "lng": -87.6297982 }, "location_type": "APPROXIMATE", "viewport": { "northeast": { "lat": 42.023131, "lng": -87.52404399999999 }, "southwest": { "lat": 41.6443349, "lng": -87.9402669 } } }, "place_id": "ChIJ7cv00DwsDogRAMDACa2m4K8", "types": [ "locality", "political" ] } ], "status": "OK" }

Under the key array “location” we can see the longitude and latitude of Chicago.

When you send one of these requests, you don’t know which server you are contacting or if the server is online at the moment. You may get cached information.

Using this method, you can ask for any public information (resource) that uses HTTP protocol.

If you want to POST, EDIT, or DELETE resources, you will probably have to be logged into your account. And how can you login through an API?

You would need an API Authentication Key that substitutes your login details. Once you set this, you can also post, edit, and delete resources on your own account.

Getting Started with API Testing

When developing an API, it’s important to test the product effectively. A few key considerations to take into account when developing an API testing strategy include the following:

  • What should be tested? Function and performance, as mentioned above, reflect two important areas to focus on when putting an API through its paces.

  • How to test in an efficient and effective manner? Automation is your friend. Test early and test continuously to increase the quality of the end product.

Sauce Labs API Testing offers an all-in-one solution for API testing, monitoring, and insights. Sign up for a Sauce Labs free trial to get started with API testing today.

Nov 4, 2022
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