API testing is a type of software testing that focuses on whether the development API meets certain attributes such as functionality, reliability, performance, and application security.
The interest in API testing has steadily increased over the last few years.
Having the right process, tool and solution for API testing is a very critical issue. With the “shift-left” trend, API testing is far more than a quality control solution, but also a key component of CI / CD development success.
1. SoapUI (Free or $659/yr)
SoapUI is a “headless” test tool for functional testing dedicated to testing APIs, allowing users to easily test REST, SOAP API and Web services.
Using SoapUI, users can get a complete data source and thus create priority features in addition to the following options:
- Quick and easy creation of a “drag and drop” and point-and-click functionality
- Quickly create custom code using Groovy
- Powerful “data-driven” testing: Data is uploaded from files, databases or Excel documents so they can simulate how consumers communicate with my API
- Creating complex scenarios and supporting asynchronous testing
- Reuse Scripts: Security and read data tests can easily be reused for functional test scenarios in a few steps
Web site: https://www.soapui.org/
2. Postman (Free or $21/user/month)
The Original Chrome Tool, Postman has now expanded its solution to the original versions of MacOS and Windows.
Postman is a good choice for API testing for those who do not want to go into coding with coding and integrated development using the same programming language as developers.
- Easy-to-use REST client
- A rich interface that makes it easy to use
- It can be used for both automatic and investigative testing
- It can run on MacOS, Windows, Linux, but also on Chrome apps
- There is a lot of integration, such as support for Swagger and RAML formats
- Has Run, Test, Document and Monitor Functions
- It does not require learning a new programming language
- Allows users to easily share knowledge with the team by covering all the requests and expected responses of the app and then forwarding it to colleagues
Web site: https://www.getpostman.com/
3. Katalon Studio (Free
Katalan Studio is a free automation test tool that provides a common environment for creating and executing UI functional, APIs, web services, and mobile tests.
The ability to combine UI and Business Level (APIs or Web Services) for different environments (Windows, MacOS, Linux) is considered a priority for Catalan Studio.
Catalan Studio supports SOAP and RESTful requests with a variety of command types (GET, POST, PUT, DELETE) with the ability to change parameters.
- Supports a combination of tests between UI and API Verification
- Supports both types of requests, SOAP and RESTful
- Hundreds of embedded keywords for creating test scenarios
- Supports one of the most powerful Asset library, AssertJ for creating comprehensible BDD queries
- Supports a “data-driven” approach
- It can be used for automated and investigative testing
- The tool is suitable for professional and non-technical persons
Web site: https://www.katalon.com
4. JMeter (Open Source)
- JMeter is widely used for functional API testing although it is actually created for “load” testing.
- Provides broad support for repetition of test results
- Automated work with CSV files, allowing the team to quickly create unique API test benchmarks
- Users can include API tests in “CI Pipeline” with the help of integration between JMeter and Jenkins
- It can be used for static a and for dynamic performance testing resources
Web site: https://jmeter.apache.org/
5. Rest-Assured (Open Source)
- Rest-Assured is an “open-source” Java language, which makes REST service testing much more extensive.
- There are a lot of built-in functionalities, which means users do not have to encrypt things from scratch
- It integrates seamlessly with the Serenity framework for automation so that users can combine UI and REST tests into one freeware that generates extraordinary reports
- Provides support for BDD Given / When / Then syntax
- Users do not have to be HTTP experts
Web site: http://rest-assured.io/
Also, there are other popular API testing tools such as:
Tricentis Tosca (https://www.tricentis.com/)
Karate DSL (https://github.com/intuit/karate)