Understanding Insomnia REST Client Made Easy 101

Dipayan Mitra • Last Modified: December 29th, 2022

Insomnia REST CLIENT - Featured Image

 Application programming interface (API) testing is a type of software testing that helps developers analyze whether the software fulfills the expected security, performance, functionality, and reliability. These tests intend to determine any unexpected behavior, errors, and bugs before the product goes into development. Insomnia REST Client is one such API testing tool that supports RESTful applications. The API tests are performed either as part of integration testing or directly on the API.

This guide will cover the benefits of API testing and introduce you to the Insomnia REST client. You’ll also uncover the features of Insomnia and how to test your REST APIs with the Insomnia REST client. 

Table of Content

Introduction to API Testing

Application programming interfaces (API) is the connecting tissue between different layers (Data layer, Service layer, and Presentation UI layer) of an application. It contains rules of how users can connect with data, services, or functions of applications. Although Traditional API testing focuses on the presentation layer, API testing has a multitude of advantages. 

API testing checks the Reliability, Performance, Functionality, and Security of the programming interfaces. API testing doesn’t concentrate on the look and feel of the software but rather focuses on the logic layer of the architecture. An API test involves testing one or more API endpoints and comparing responses with expected results. 

Key Features of API Testing

  • Access Without UI: A fundamental advantage of API testing is accessing applications without interacting with the system or user interface. QA testers can run API tests without using or experiencing software applications. It’s a significant advantage because this provides QA engineers early insight into errors and defects of applications. This, as a result, helps developers resolve the problems before they affect the Graphical User Interface (GUI).
  • Test for Core Functionality: API Testing allows QA engineers to examine the code-level functionality of an application before running GUI tests, providing an early evaluation of its overall build strength. Test for core functionality helps expose the minor errors that are causing apps to run slower. Core access enables testing in tandem with API development, fostering improved communication and collaboration between testing and development teams. This is especially helpful if an offshore QA team is performing the API testing.
  • Time Effective: One of the significant differences between GUI and API testing is that the former is far less time-consuming than functional GUI testing. GUI testing is comparatively slow since it requires the polling of webpage elements. At the same time, API testing is known for quick results. Because API testing requires less code, it provides better and faster coverage than automated GUI tests. 
  • Reduced costs: The cost-efficiency benefit of API testing is closely connected to its time effectiveness. Increased execution speed leads to more efficient resource consumption and more inexpensive testing costs. Unlike GUI, testers can execute API tests as early as the business logic is defined to identify the issues at an early stage. Early identification ensures that minor issues don’t become a production problem, keeping project costs at bay.
  • Language-Independent: An API test exchanges data using JSON or XML. Both XML and JSON transfer modes are completely language-independent, allowing testers to select any core language when pursuing API testing of your application.

Introduction to Insomnia REST Client

Insomnia REST Client is a powerful REST API client used to organize, store, and execute RESTful API requests elegantly. Insomnia is one of the fast REST clients that’s available for Windows, Mac, and Linux. Insomnia REST client is a Free Cross-Platform Desktop Framework for testing RESTful applications. It incorporates sophisticated features like code creation, security helpers, environment variables, and a user-friendly user interface. You can take advantage of Insomnia to test GraphQL APIs and HTTP-based RESTful APIs. It’s an excellent alternative to Postman for sending GraphQL and REST requests with support for environment variables, cookie management, authentication, and code generation. 

A) Pricing

Insomnia REST Client - Pricing Details
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Insomnia has three pricing structures: Free, Individual, and Team. The free plan comes with free updates, API client, Design APIs, Test APIs, and community support. The individual plan costs $50 per user/year and provides access to unlimited devices and E2EE Sync. The team plan costs $120 per user/year and provides access to more features like user management, priority support, and E2EE Team Sync. 

B) Plugins

The Insomnia Plugin Hub has a wide range of useful extensions, and the platform makes the search for plugins much more accessible. Since it is still relatively new, you might not find the desired plugin for your project. With the Insomnia REST client, you can download Insomnia-supported plugins or design a dedicated custom plugin for your API testing. 

  • Downloading plugins: There are two ways to install a plugin in Insomnia. You can either install it directly in Insomnia using the name of the NPM package or install the plugin by clicking on a button on the website. 
  • Design Plugins: You should have your plugin as a NodeJS module, and it must be placed in a specific directory for Insomnia to recognize.

Plugin File Location for each OS is as follows:




C) Key Features of Insomnia REST Client

  • Exportable Workspaces: One prominent feature of Insomnia is the ability to export and share workspaces. It is helpful when your team members want to use an Insomnia workspace that you’ve built up throughout the project. Rather than having every member meticulously copy each request, you can export a JSON document for your environment and share it with your team.
  • Swappable Environments: Insomnia allows you to set environment variables that your company’s testers can reuse across multiple requests. For example, you can set a base_url variable and use that across many requests to hit different REST endpoints on that URL. Swappable Environments’ usefulness amplifies when combined with the ability to swap between various sets of environmental variables. For example, most projects have different backend, URL, and HTTP authentication credentials for development, testing, and production. This feature eases the friction of switching between those URLs by allowing users to create an Insomnia environment for each backend. Having a base_url, username, and password in each environment enables users to switch between and test each environment quickly.
  • Chained Requests: The next significant feature of the Insomnia API testing client is the ability to chain requests. When you have an endpoint that provides a token to access other endpoints, you can set up a request that hits a generated token endpoint, then use its response with other endpoints.
  • End-To-End Encryption: Insomnia comes with E2EE, which means that encryption is performed before sending any data over the network, keys are generated locally, and decryption is performed after receiving data from the network. E2EE ensures that neither Insomnia servers nor an intruder can read or access sensitive application data. Additionally, all data is encrypted using randomly generated 256-bit symmetric keys for use with AES-GCM-256.

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  • Knowledge of APIs testing
  • Insomnia REST client

Testing REST API with the Insomnia REST client

Follow these steps to test your RESTful application with the Insomnia REST client:

Step 1: Install Insomnia

You’ll need to install the Insomnia REST client on your machine. To do so, go to the official Insomnia website to install the relevant version on your machine. Insomnia REST client is available to download for Windows, Linux, and Mac. 

Step 2: Check your REST API Docs

Your RESTful API will have docs to guide you through the testing process. Read through them and figure out the details such as the base URL, headers or params that are required, need for a request body, JSON format, etc. 

Step 3: Make your 1st HTTP GET Request

Insomnia REST Client - New Request Option
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Once the Insomnia REST Client app is open, you’ll see a mostly blank workspace. To make your first request, click on the plus icon, which will trigger a drop-down giving you the option to make a New Request or create a New Folder

Insomnia REST Client - GET Request
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To create a GET request, follow the steps outlined below:

  • Step 1: Launch the Insomnia REST Client application.
  • Step 2: Click on the “New Request” button.
  • Step 3: In the “New Request” window that pops up, specify the name of the request and select a request method.
  • Step 4: Click on the Create option.

Step 4: Send a POST Request

Insomnia REST Client - POST Request
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Assuming that Insomnia is up and running to send a POST request, follow the steps outlined below:

  • Step 1: Specify the URL in the address bar.
  • Step 2: Specify the JSON data in the request body.
  • Step 3: Click on the Send option.

The response returned as true, showing that the POST request was successful. Similarly, you can make a PUT, PATCH, and DELETE request. 


In this article, you have learned about the Insomnia REST Client and how to effectively test your REST APIs with the Insomnia REST client. Every API has a particular action (update data, trigger an event, set a flag, or change the registry). API testing helps developers check if the API is returning the designated action. Insomnia is a Free Tool for Testing and Validating Results of RESTful applications that comes with exceptional features like sharable environments, plugin hub, end-to-end encryption, and much more.

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Share with us your experience of working with the Insomnia REST Client. Let us know in the comments section below!  

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