Best Automated API Testing Tools for 2023

LINET M SHAJI | December 21, 2022

Best Automated API Testing Tools for 2023

Many of the software products we use daily now rely on different interconnected APIs , if any one of the APIs is not functioning well then the entire application will be at risk. Having a product that matches the requirements specified by the client is very important. We can ensure it by testing the product effectively before it is delivered. Software testing can be done manually or automatically by using automation tools. Manual testing is the process of testing an application manually like a user without using any tools. In the case of automation testing, testing will be done by using automated testing tools. Before testing the entire software, we must ensure that APIs designed by developers meet the requirement and perform well. Using API testing tools we can ensure that the APIs meet the requirements and perform well without any bugs. Now we have a lot of API testing tools available in the market. Below are a few popular API testing tools-

Swagger UI

Swagger UI allows its users to interact with the API resources without having any implementation logic.


  • Swagger Inspector enables us to inspect API requests, and responses and ensure they work properly.
  • It can validate schema rules by importing the user’s API definitions.
  • It generates assertions automatically against endpoints and injects synthetic data into parameters.
  • It generates complex load scenarios to analyze API performance.
  • It supports all types of services including SOAP, REST, and GraphQL.


SoapUI is a functional testing tool that supports REST and SOAP testing. Easy to create and execute automated functional, regression, and load tests with SoapUI.


  • Supports data-driven testing
  • It supports REST, SOAP, JMS, JDBC, and many other protocols.
  • Users can access the complete source code of SoapUI
  • It has point-and-click and drag-and-drop functionality, simplifying complex tasks such as working with JSON and XML and rapidly creating tests.


JMeter is an open-source tool of Apache for analyzing and testing the performance of software applications. Initially, it was designed to perform load testing, now it is famous for performing functional API tests. This tool can be also used as a unit-test tool to test JDBC database connections. In December 2020, when JMeter version 5.4 was released, it started providing bug fixes and core enhancements.

  • Users can include API tests within CI pipelines by integrating Jmeter with Jenkins.
  • Very flexible and allows users to customize it according to their requirements.
  • It can be used to test the performance of both dynamic and static resources.


Postman is a google chrome plugin for developers to design, build and test APIs. It is a simple testing platform for sending and viewing HTTP requests and responses. This tool can make various HTTP requests such as GET, POST, PUT, DELETE, etc.


  • Use of collections - Postman allows users to create collections for our API calls.
  • Collaboration - It allows us to import and export collections and environments, which makes it easy to share files. We can also use direct links to share collections.
  • Creating environments - We can create multiple environments that help us avoid the repetition of tests so one can use the same collection but for a different environment.
  • Creation of tests - To test checkpoints, verification of response status code added to all API calls.
  • Debugging - Postman console helps us to keep track of what data has been retrieved, which makes debugging tests easier.
  • Automation testing - Tests can run in multiple iterations by using Collection Runner or Newman, which helps us to save time for repetitive tests
  • It supports continuous integration


Katalon is a software quality testing tool that allows us to test web, mobile apps, and APIs.


  • It supports REST, SOAP, and SSL client certificates
  • It supports AssertJ to create fluent assertions in the BDD style
  • It supports Both automated and exploratory testing
  • It has Native CI/CD integrations like Jenkins, Azure DevOps, CircleCI, Dockers, etc.
  • It supports test import from Swagger (2.0 & 3.0), Postman, WSDL, and WADL
  • It supports the data-driven approach

These are commonly used API testing tools. There are many other API testing tools available in the market. When choosing an API testing tool it is important to consider our needs, each tool has common features and its own special features. Based on our needs we can choose one or more API testing tools.

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