How to Work With Postman REST Client: The Complete Guide

Postman is an API advancement environment that is used to test APIs, make robotized tests, get data or responses from your requests, and lots more. 

It is one of the most scalable API testing tools that can be easily inserted into the CI/CD pipeline. This is one of the reasons why Postman holds an edge over other REST Clients for API Testing. 

Using Postman REST API Client, you can make your process of creating, sharing, testing, and documenting APIs easier.

In this blog, you will be introduced to the Postman REST Client and understand the installation & working of it. You will also be exposed to the GET and POST requests to retrieve and manipulate data from a specified URL.

What is Postman REST API?

Postman is an Application Programming Interface (API) development platform that helps you build, test, and modify APIs. It simplifies every step of the API lifecycle and streamlines collaboration allowing you to create better APIs. 

Postman started as a REST client and it has now completely evolved into a comprehensive API platform.

Representational State Transfer or REST is basically a standardized Software Architecture Style for building the HTTP services used to establish communication between client and server. You can easily implement the REST API approach by using Postman REST Client. 

You can use Postman REST Client to invoke a REST Service API to create and execute queries.

Postman boasts of almost all functional tools needed by developers as they are encapsulated on the platform thereby making it a popular API platform used by over 5 million developers monthly. 

It can handle various types of HTTP requests ranging from GET, POST, PUT, to PATCH, converting the API to code for other languages like JavaScript, Python, etc. Postman can also save your environments for later use.

Some of its key features are:

• Seamless automated testing.
• Collaboration features for effortless sharing and management.
• Supports Swagger and RAML (RESTful API Modeling Language) formats.
• Offers powerful visualization compatibility.
• Supports multiple protocols, manages cookies, and manages certificates.

Why Postman REST API is preferred?

Postman REST Client software is gaining attention nowadays because of its exciting features. The main reason for choosing Postman REST Client is its Accessibility. Postman REST Client serves a lot of purposes like sending requests and inspecting responses.

Using Postman REST Client, you can easily debug REST APIs. Postman REST API comes with a very easy-to-use user interface with which you just need Postman installed on your PC. You can access your files anytime and anywhere, which makes the entire process easier.

Postman REST API software also provides an option to create collections for their Postman REST Client API calls. These collections will also have subfolders and can make multiple requests.

Using Postman REST Client, you can easily import and export files. You can have a direct link to share files with ease. Postman REST Client provides you with multiple environments. These multiple environments will reduce the number of repetitions of tests for the same collection for various environments.

With Postman REST Client software, you can create test checkpoints. These test checkpoints verify each successful HTTP response status and update the Postman API calls. This ensures entire test coverage.

Postman REST Client software has got the automatic testing option with Collection Runner or Newman. With this, you can run multiple iterations parallelly and avoid repetitive testing. Postman REST Client is really easy to debug and retrieve. It also gives a continuous integration option.

Postman Installation

Postman is an Open Source tool, and hence can be easily downloaded. Here are the steps in Postman Installation.

Step 1: Download your device’s compatible version of Postman from this link. Click Download to get the setup downloaded.

Step 2:  After running the .exe file downloaded. Now signup for a Postman Account.

Step 3: Next set up your workspace tools by selecting them. Just click and save your preferences.

Step 4: It is all set now! Your Startup Screen will look like this.

How to use Postman to execute APIs?

Here is a detailed view of all the features and processes of Postman REST API. A Postman Workspace picture is shown below.

1. New – Using this you can create new requests, collections, or environments.
2. Import – You can import a collection or environment with this. You also have options such as import from file, folder, link, or paste the raw text.
3. Runner – You can run automation tests using the Collection Runner.
4. Open New – Using this you can open a new tab, Postman Window or Runner Window.
5. My Workspace – With this, you can create a new workspace individually or as a team.
6. Invite – This is used to invite team members for workspace collaboration.
7. History – You can keep a track of all your past requests in this History.
8. Collections – This is used to organize all your test suite using collections.
9. Request tab – This tab will show the title of the request that you are currently working on. The default title is “Untitled Request”.
10. HTTP Request – This dropdown has different HTTP requests like GET, POST, COPY, DELETE, etc. In Postman REST API testing, GET and POST are frequently used.
11. Request URL – This is also named as an endpoint. Using this you can identify the link to your API’s communication.
12. Save – You have to save all the new changes when made. Else they will be lost or overwritten.
13. Params – You have to enter all the parameters required for a request like key values.
14. Authorization – Authorization is required for safe access and it will be in the form of a username and password, bearer token, etc.
15. Headers – Based on your organization’s requirement, you can choose headers such as content type JSON.
16. Body – You can customize the request details here.
17. Pre-request Script – These scripts are used to verify if the test is running in the right environment. This is executed before the actual request.
18. Tests – You have to execute these scripts during the request. All these are used as checkpoints to verify the response status, data retrieved, and other tests.

Postman REST Client features

Postman REST Client: Send Requests and View Responses

Postman REST API is used to create complex requests, pick up the pace during query execution, and verify responses. You can create and execute queries using Postman REST Client.

Create complex requests

Using Postman REST Client, you can send all the types of requests. You can define and save customized requests and send them using these body types.

• URL-encoded: This is the default type used to send simple text data.
• Multipart/form-data: This is used to send data in large quantities of non-ASCII text or binary data.
• Raw body editing: This is used to send data when encoding is not required.
• Binary data: This is used to send other file types like images, audio, or video.

Fast execution

Postman REST Client is one of the best alternatives for manual call creation and sending them over the command line. To use Postman REST Client for fast execution, you can directly import a collection. You can also generate from an API schema in the RAML, WADL, OpenAPI, or GraphQL format or a data file with the cURL commands.

Verify responses

Using Postman REST Client, you can inspect responses. You can view the status code, response time, and response size easily using Postman REST Client. Postman has an automatic language detection option in it. You can link and highlight syntaxes, search, and format texts easily using Postman REST Client.

Postman REST Client: Visualize Your Data

Postman REST Client has hot a Visualizer that can easily convert your API data into graphs and plots.

Using Postman Visualizer you can avail the following benefits:

• Build your own visualization style: You can make use of HTML5, JavaScript, and CSS to build your own visualization pattern. You can also bring in the existing charting and graphing libraries to make meaningful visualizations.
• Make use of the powerful inbuilt visualizations: Instead of making use of the API JSON or XML responses, you can go one step ahead. If you are an API consumer, you can get more from the data you have in hand. Postman REST Client provides you with inbuilt charts and graphs for visualizations.
• Share these visualizations with your teams: You can share your visualizations easily in a single click with your fellow team using Postman collections.

Postman REST Client: Built-In Support for Variables

Using Postman REST Client, you can reuse values in more than one place with variables. By this, you can retain your code and requests DRY.

• Create variables in multiple scopes: Using Postman REST Client, you can store the values at the global level, environment level, and also collection level. You have the liberty to add variables to the URL, URL parameters, headers, authorization, request body, and header in the Postman REST Client directly.
• Fast diversified requests: You can use these environments to move between various setups without altering your requests, All you need to do is to choose the correct environment to update all your variables.
• Safeguard information with session variables: You can manage all your high-priority sensitive data like API keys by storing them in session variables which will stay local in your own machine. This will never sync with your fellow teammates.

Postman REST Client: Manage Authentication

Postman REST Client provides you with access to the APIs even without the authentication protocols.

• Handle multiple protocols efficiently: Postman REST Client comes with inbuilt support authentication protocols like OAuth 2.0, AWS Signature, Hawk Authentication, and more.
• Manage cookies: Postman REST Client manages cookies very effectively. It gets the cookies that are back from the server while making a request. It saves these cookies and later uses them in other requests. Postman REST Client will also help you to add cookies and customize your domain.
• Manage Certificates: You can manage your certificates using Postman REST Client. In this, you have the option to view see and fix the SSL certificates according to the domain need. When you add a client certificate, it will eventually reach a request to that domain over HTTP.
  The certificates that Postman REST Client generally supports are SSL certificate validation, the Custom root CA Certificate support, and Client certificate support.

Postman REST Client features: Postman Addon

Postman REST Client is one of the most powerful tools for API exploration and development. Apart from the features discussed already, here are some additional features of the Postman REST Client.

• Track request history: Postman REST Client helps you to track all your request history. All the requests sent are stored and can be viewed in the “History” tab. You need not waste time by building everything from scratch.
• Generate code snippets: You can generate your request code snippets using different frameworks and languages using the Postman REST Client. You can also use the same request from your own application.
• Write tests in Postman Sandbox: You can test your scripts and add dynamic behavior to requests and collections. You can also write test suites, build requests that contain dynamic parameters, pass data between requests, and more.

Working with GET Requests

You can use GET requests to retrieve data from the specified URL. No change will be made to the endpoint. For this example, we’ll use this URL:

https://jsonplaceholder.typicode.com/users

Here are the steps that you must follow:

1. Set your HTTP request to GET.
2. In the request URL field, enter the link.
3. Now, click Send.
4. You will see 200 OK Message
5. There should be 10 user results in the body which indicates that your test has run successfully.

Working with POST Requests

Post requests do data manipulation with the user by adding data to the endpoint.

Step 1: Create a new request by selecting the new tab.

Step 2: Now do these modifications in the new tab.

1. Set your HTTP request to POST.
2. Enter the same link in the request URL: https://jsonplaceholder.typicode.com/users
3. Now switch to the Body tab

Step 3: After this, select raw and JSON in Body.

Step 4: Copy and paste only one user result from the previous get request like below. Now alter the id to 11 and name to any desired name. And also change the address details.

Step 5: Next select Send. Then Status:201 Created will be displayed in the bottom. Now you can see that your data posted in shown in the body.

Postman REST Client Use Cases

Postman REST Client use cases include API-first development, developer onboarding, automated testing, and more. Let’s discuss them in brief.

• API-First Development: Postman allows you to build your API for releasing reliable applications and services even before deploying the code. The schema support gives you visibility into your API specifications and structure. So, so you can easily ship higher-quality applications before writing code.
• Automated Testing: This feature gives users the flexibility to automate their API tests with Postman. You can seamlessly automate the manual tests and save a lot of valuable time. Automated testing can also be integrated into your CI/CD Pipeline to ensure that any modification in the code won’t break the API in production.
• Developer Onboarding: Postman is very interactive and easy to use. It comes with built-in schema support, shared knowledge in workspaces, and more just to help you learn and develop faster.
• Application Development: Postman makes application development a walk in the park. With Postman, you can eliminate dependencies and reduce production time by giving the front-end and back-end teams the flexibility to work in parallel.
• Exploratory Testing: This is one of the important use cases of Postman as it allows you to explore the APIs by sending different kinds of data requests and inspecting the responses. You just need to import or generate a Postman Collection and use the built-in library of dynamic variables to generate dynamic dummy data for testing multiple iterations.
  You can also use the Postman Sandbox to write tests and also share them with your teammates.

Frequently Asked Questions (FAQs)

1. Does Postman support REST?
Yes, Postman offers a REST Client that allows users to easily debug REST APIs. You just need Postman installed on your PC to access its REST CLient and it is a very easy-to-use user interface.

2. Is REST API and RESTful API the same?
A REST API is an Application Programming Interface (API) that follows a set of rules for interaction between applications and services. Considering the debate on REST vs RESTful APIs, it can be stated that “REST is the noun while RESTful is the adjective”. The RESTful API obeys the REST architecture constraints and interacts with RESTful web services.

3. Is REST API always JSON?
Some sources define REST as a server that exchanges JSON documents with a client over HTTP. However, this is not always true as the REST specification doesn’t require HTTP or JSON.

4. Can I Automate Postman?
Yes, Postman can be automated to perform various types of tests including unit tests, integration tests, functional tests, end-to-end tests, mock tests, regression tests, etc. Automated testing doesn’t require human intervention and streamlines testing.

5. Can REST API use XML?
Yes, you can always create a REST API with XML as the response. You can even use any number of the XML libraries available on npm to generate an XML response.

Check out our blog on connecting Postman to Salesforce.

Conclusion

Postman is one of the most scalable API testing tools available in the market. It simplifies every step of the API lifecycle allowing you to create, share, test, and document APIs easily. 

Postman REST Client serves a lot of purposes like sending requests and inspecting responses. It further allows you to visualize your data and also provides in-built support for variables.

This blog introduced you to Postman and its REST Client and showed you how to execute APIs using Postman. Later, it took you through various key features of Postman REST Client and helped you work around GET and POST requests.