Software testing by Unify

API Automation Testing Tools

API Automation

Modern applications rely on micro-services and data from many sources to provide the functionality required by the business. All of this is based on API’s, so their integrity and robustness is vital.

Some example tools to help with API test automation include:

REST Assured

  • A Java library that allows interaction with HTTP based REST APIs.
  • Simple to write tests in and assert truthfulness of responses.
  • Does require some Java knowledge to design and develop tests.
  • This library is open source and free.
  • Can be found at



  • A standalone REST client that allows codeless tests to endpoints.
  • Very easy to use, the codeless nature allows you to create tests quickly with smaller margin for error.
  • Using Numan, test can be executed via in CLI.
  • This tool is free but has a licensed ‘pro’ option for more features.
  • Can be found at



  • A more complex Soap client that integrates with SOAP APIs
  • More weighted towards complex APIs with heavy dependency on QA/testing.
  • Can create custom workflows in Groovy, which provides better efficiency.
  • This tool is free but has a licensed ‘pro’ option.
  • Can be found at



  • A Java application more focused on performance and load testing, JMeter can still offer powerful functionality to test REST APIs.
  • A codeless but complex test design style, tests are built with custom objects in a test plan, which there are public plugins to extend the functionality.
  • Allows for API response assertions and also able to load these APIs to test the performance.
  • Integrates very nicely into CI/CD as JMX files that can be run from CLI.
  • This tool is open source and free.
  • Can be found at


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