5 Best API Automation Testing Tools


Subscribe to our Newsletter

APIs (Application Programming Interface) is now a regular subject of discussion like many businesses out there if they’re not already being thought about constantly. In reality, with just an API GUI, many of the fastest-growing businesses such as Stripe, Twilio, and Plaid are growing in sales to billions of dollars. 

Top API Automation Testing Tools

In this post, we will concentrate primarily on the top API automation testing tools on the market that you should keep a close eye out for.

1. Postman

The first method that comes to mind is Postman when it gets to API checking. With more than 11 million users, Postman is easy to adopt by expert users for beginners up. The tool can be used to interpret and discover APIs, and then also to build and execute automated scenarios using those findings later. It was first conceived as a Chrome extension but has grown to include localized Mac & Windows versions, making the solution suitable for those without much programming effort who want to test APIs.


  1. It is a type of test automation tool that supports API development, both exploratory and automated.
  2. A nice client that supports REST and SOAP APIs and is easy to use.
  3. Installation support for Mac, Windows, and Linux.
  4. Support for Swagger concepts, support for RAML formats & requests for GraphQL and schemas.
  5. Provides functionality for running, checking, logging & tracking.
  6. Support for 23 + encoding languages, including Java, C #, Python, and JavaScript.


  1. An upgrade to the paid version is required for some of the added features and increased restrictions.
  2. The free plan comes with a limit on the number of applications that are shared.

Also Read: 9 Steps To Automate Your API Testing With Postman

2. SoapUI

SoapUI is a Full API Management Platform from SmartBear, which enables users to test REST, SOAP, and other APIs quickly. They sell an open-source edition and a feature-enhanced paid version. It is one of the headless API automation testing tools that provide comprehensive scripting options, using either Groovy or JavaScript, allowing complex testing situations to be generated and custom features to be added. 


  1. The capabilities of coding allow users to build complex scenarios and facilitate simultaneous testing.
  2. Using an assumption wizard, form editor, an SQL query builder (Pro Package), it is simple to construct end-to-end test automation from the user interface.
  3. Support for data-driven experiments to model customer scenarios with APIs
  4. Native integration with common tools such as Jenkins and Bamboo for building.
  5. Virtualization of services to assist in imitating online services before they are introduced.
  6. The Endpoint Explorer dialogue has been added to allow users to submit exploration requests and review feedback without creating a new project.


  1. Many features are restricted to pro (ReadyAPI) offerings, which are costly.
  2. For scripting, limited to Groovy / JavaScript.
  3. In contrast with the market, less efficient collaboration choices.

3. Rest-Assured

REST-Assured is indeed an open-source Java application that provides efficient, controllable tests for RESTful APIs in a domain-specific language (DSL) for writing. For accessing REST facilities, it serves as a headless client. It also helps us to test a large range of combinations of requests and verify the HTTP responses obtained from the server.


  1. With several templates and libraries given out-of-the-box, it is easy to get started.
  2. The Serenity automation system can be easily incorporated, which helps to combine the UI and REST tests in one system that produces awesome reports.
  3. Support Syntax for BDD Given / When / Then.
  4. Simple TestNG / JUnit integration.
  5. Users don’t even have to be an expert on HTTP.


  1. Java language is supported.
  2. Support for the REST API protocol only.

Rest-Assured is a great choice if you are looking for an API testing tool that supports a BDD style specification and you use Java.

4. TestProject

TestProject is a robust automation platform for end-to-end tests that supports Web, Mobile, and API testing. It is a culture-powered, cloud-based test automation platform. The layered approach of TestProject enables users to collaborate, exchange, and perform tests with ease from anywhere & without much effort. It offers support for REST API testing with the aid of an add-on.


  1. Forever available.
  2. End-to-end testing is supported, including UI (Web and Mobile) and API testing.
  3. One-click local agent installation for Windows, Mac, and Linux.
  4. Data-driven testing with capabilities to import CSV.
  5. Assimilation of CI / CD into Jenkins.
  6. Interesting reports and analytics can be exported as a PDF file.
  7. Suitable via scriptless recorder (with export to SDK) for pros and non-techies.
  8. Active Group of 25,000 + users with easy live chat support.


  1. Support for the REST API protocol only.
  2. As a web project, API tests have to be developed first, which makes it challenging for certain users.
  3. It is a little difficult to tackle version control and Release Management Integration.

If you need to provide a single tool that is simple to use & set up for API, web, and mobile apps, then TestProject is a great option.

5. Karate

Karate is a platform for API testing that is open source. It is based on a cucumber library and, without needing step definitions; it helps to quickly build API-based BDD tests. KarateDSL creates such definitions to help users easily conduct API testing. Karate is a cohesive platform for automating API tests, mocks, testing results, and even automating UIs.


  1. Made with the familiar Cucumber-JVM on top.
  2. As with any Java project, standard test running and generating reports.
  3. The abstraction layer enables non-technical users to build experiments.
  4. API and UI automation can be combined within the same test script.
  5. Re-usability of performance assessments for practical tests.
  6. Simple to integrate with CI (JUnit, TestNG, etc.) through supported test runners.
  7. Help for GraphQL, REST, and SOAP checking.
  8. Supports multithreaded parallel switching of execution and configuration.


  1. Only JavaScript extensions can be written.
  2. The Auth Schemes tool is not out of the hat.
  3. Help from TestNG is obsolete.

Karate is an excellent choice if you are a fan of BDD style specifications and are searching for an API testing tool that is equally powerful for newcomers and seasoned users. It is never easy to pick the right API automation testing tools, but here are some tips to bear in mind to simplify the process:

  1. Research the needs carefully and prioritize the needs of all stakeholders.
  2. Think early on about the budget so that you can determine if commercial instruments are a viable choice.
  3. Understand and rate the characteristics given by each instrument and supplier against your requirements.
  4. Involve a few trusted experts in the process of assessment.

Also Read: API Tester: Why It Matters, And API Testing Tools To Use

Contact Us

Hire vetted developers & testers with Appsierra to build & scale your software products

Trusted by 100x of startups and enterprise companies like

Read More

Subscribe to Our Newsletter