Top 10 API Testing Tools

Application Programming Interfaces (API) testing is a kind of software product testing where the testing can’t be carried out at the front-end as there is no GUI.

API testing is primarily conducted on the message layer. It includes testing SOAP Web services, REST API’s that can be transferred over HTTPS, HTTP, MQ, and JMS. This is a critical element for any Automation Testing.

Because of the characteristics of API Testing, the testing cannot be possibly carried out manually. You have to use some very good API testing tools to test the APIs. Here, in this article, we will discuss some of the highly recommended API Testing tools that you can use for your purpose.

1. Postman

Postman is one of the best tools for API testing. It has rich features and is available free of cost. It has also been recommended by most of its users.

• Supports Automated Testing.
• Helps in Exploratory Testing.
• Supports RAML (RESTful API Modeling Language) and Swagger formats.
• Supports sharing of knowledge within teams.

Also Read: Why A Business Should Opt for Test Automation?

2. SoapUI

SoapUI is great for API testing as well as Webservice testing.

• It provides help in API Mocking and Virts.
• For the statistics and metrics, it would offer you HTML reports, Printable reports, or data exporting in CSV & XML format.
• For data-driven testing, SoapUI supports test-data reading from various sources such as XML properties, Excel file, JDBC sources, directories, and files.
• It lets you use the scripts again.
• It offers numerous other features such as Click and Point testing, security scans, and Code Free testing.

3. Katalon Studio

• Supports both REST and SOAP requests, parameterization functionalities, and different kinds of commands.
• Supports the data-driven approach.
• Supports the CI/CD approach.
• Supports AssertJ, which is a great assertion library for creating fluent assertion using BDD style.
• Perfect for both experts as well as engineers with the Scripting and Manual modes.
• You can use it for both exploratories as well as automated testing.
• Customizable and pre-built code templates.
• Sample projects are given for quick reference.
• Auto-formatting, Code inspection, and Auto-completion features for the code.
• UI for creating, executing, and maintaining tests.

4. REST-Assured

REST-Assured helps in the testing of the REST services in Java domain. It’s an open-source testing tool. REST-Assured supports JSON and XML Requests/Responses.

• Seamless integration with the Serenity automation framework.
• Provides certain baked-in functionalities.
• It supports syntax of BDD Given/When/Then.
• For using this tool, being an HTTP expert is not mandatory.

5. Swagger.io

• API Design and Development.
• API Documentation.
• API Testing.
• API Virtualizations and Mocking.
• API Monitoring and Governance.

Also Read: A Complete Guide to Dos and Don’ts of Test Automation

6. JMeter

This tool is highly recommended for testing Load and Performance of web applications.

• It will let you use many different programming languages.
• Helps in testing Load and Performance of various applications, protocols, and servers.
• Replaying the test results is possible with JMeter.
• It supports variable assertions and parameterization.
• Supports per-thread cookies.
• Variety of reports and configuration variables are supported by this testing tool.

7. Karate DSL

This tool has been specially developed for Automated API Testing. You do not require programming language for using this testing tool.  However, the basic knowledge of JSON, HTTP, JsonPath, XPath, and XML would be an additional benefit.

• Supports Multi-threaded parallel executions.
• Report generation.
• Allows configuration switching.
• Supports Payload-data reusing for API Testing.

8. Airborne

This is an open-source Automated API testing framework. It is Ruby-based RSpec driven. This testing tool does not have UI. It only provides a text file for writing the code.

• It works with the APIs that are written using Rails.
• For using this testing tool effectively, you should know RSpec and Ruby basics.
• It works with Rack applications.

9. Pyresttest

This testing tool is based on python and has been designed for testing RESTful APIs. It is even a Micro-benchmarking tool. It supports the JSON configuration files.

• For the failed results, exit codes are returned.
• No code is required.
• Building test scenarios using extract/generate/validate mechanisms.
• Due to the lowest dependencies, Pyresttest has simple deployment on the server that is necessary for the Smoke Testing.

Also Read: Best Automation Testing Tools for 2019

10. Apigee

Apigee is a cross-cloud API management platform. It offers governance and security policies to APIs. With Apigee, you can design, analyze, scale, and secure APIs anywhere.

• It offers customizable developer platform.
• It supports Node, js.

Out of the above mentioned best API Testing tools, SoapUI, Postman, Swagger.io, and Katalon Studio offer paid and free plans. Whereas JMeter, REST-Assured, Airborne, and Karate DSL are open-source tools that are available free of cost.