How to Use Postman to Test an API

August 22, 2022 Abraham Smith

Application programming interfaces (APIs) play an essential role in software development. If you intend to develop an online application or website, you must either create an API, use an existing one, or both.

An API takes a request from one software application to another and then returns to the initiating software with a relevant response. Therefore, if your API is broken, your application will experience problems. The Postman platform helps you keep your APIs working by providing API testing, among other useful features.

What is postman?

Postman is a platform that helps you work with APIs. It is an API repository that allows you to store, organize and use your APIs. Postman’s repository is cloud-based and versioned, making it the ideal platform for collaborative API development, as well as API development across multiple devices.

Postman lets you manage every aspect of the API development workflow. This platform has everything you need to test a full CRUD API. Postman’s popular features include:

specifications
documentation
Workflow Recipes
Testing
metrics

Install Postman on your device

You can download Postman from its official website on a Windows, Apple or Linux computer. Selecting your machine type will start an automatic download of an executable file. This installs the Postman platform in a few simple steps.

How to create requests with Postman

The latest version of the Postman platform (v9.28.1) starts with the following user interface:

To make a request to an existing API, click New Button in the top left corner of the Postman UI. This will bring you to the following pop-up window:

The top left corner of the popup window has an option to create one simple HTTP request. Selecting this option will take you to the following interface:

There are several important fields in the request interface. The first field to note is the request method (or verb) field. The default request method is RECEIVEbut there are over 10 different methods to choose from.

The five methods you will use regularly include:

GET: Acquires data from a database.
POST: Adds new data to a database.
PUT: updates an entire data field in a database.
PATCH: updates certain aspects of a data field in a database.
DELETE: deletes data from a database.

The URL field is right next to the request method field. To test an API, simply select the request method and provide the appropriate URL.

Testing a public API in Postman

You can use any public API in this section. The following example uses a news API called Newsdata.io. This API has multiple query options that return worldwide messages. The country-based endpoint has this structure:

https:

You have to replace them YOUR_API_Key Value in the URL with the API key you get after registering with Newsdata.io. Pasting the updated URL into Postman will return output similar to the one below.

{
"status": "success",
"totalResults": 10173,
"results": [
{
"title": "Apple could be the first to use TSMC's 3nm chip process for M2 Pro",
"link": "https://appleinsider.com/articles/22/08/18/apple-could-be-the-first-to-use-tsmcs-3nm-chip-process-for-m2-pro?utm_medium=rss",
"keywords": null,
"creator": [
"[email protected] (Mike Peterson)"
],
"video_url": null,
"description": "Apple's 2022 MacBook Pros may pack new M2 Pro and M2 Max chipsets made with TSMC's latest 3nm manufacturing process, according to a new report.M2TSMC, the world's largest semiconductor contract manufacturer, has been steadily building out its 3nm production processes. According to the Commercial Times, Apple could be the first customer to get its hands on those chips. Read more...",
"content": null,
"pubDate": "2022-08-18 15:22:53",
"image_url": null,
"source_id": "appleinsider",
"country": [
"united states of america",
"united kingdom",
"india",
"australia",
"singapore",
"canada"
],
"category": [
"technology"
],
"language": "english"
},
],
"nextPage": 1
}

The postman returns a series of messages. The output above shows just a sample of these news stories.

Now you can test APIs with Postman

Postman is a popular platform that you can use to test APIs that you plan to use in your projects. You can manage a range of resources and use a range of request methods.

After testing your APIs, the logical next step is to integrate them into your applications.

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