6 of the Best API Testing Tools in the Market

API test is a significant part of a successful Continuous Integration/ DevOps practice. As per Google Trends, the interest in Web/ API services tests has been progressively growing over the few decades. According to SmartBear research over 3,372 software professionals in API test over 2019, 91 percent of participants either presently have, or thinking to have a formal API test procedure in place in the coming future. Around 45 percent of API testers reported that their company already automated 50% or more of test projects. Moreover, by more than 75 percent of companies across industries, API quality is considered a top priority.

With APIs more and more becoming crucial elements for software development, it has become critically essential for programmers and developers to carry out API testing. API test is a procedure that concentrates on identifying whether an API that has been developed meets up the expected threshold concerning security, reliability, performance, and functionality. As these tests are crucially vital, you need to make use of the top API testing tools out there. 

Major Points to Consider for API Tests:

•    API consumer or Target Audience

•    Test for normal situations

•    Testing aspects

•    The surroundings in which the API is going to be used

•    Tests for negative tests or abnormal conditions

Why Execute API Testing?

As more and more companies make the shift left toward continuous deployment (CD), continuous integration (CI), and DevOps, test feedback requires being faster than ever. Concentrating completely on User Interface automation which is particularly time-consuming could kill your automation testing efforts. As you scramble to ensure that your apps are prepared to ship, API tests must be a component of your complete automation strategy.

APIs are the base of new and advanced software development, as more and more teams move away from monolithic apps and start adopting a microservices technique for software development. Through microservices that are making up the backbone of most modern development efforts, API tests turn out to be even more crucial than before.

Top 6 API Testing Tools Available on the Market

Because of the API test’s nature, it cannot be manually tested, and we have to go for some best of the API test tools to tests APIs.  Here, I have compiled a list of the top API testing tools in the market.

1. Katalon Studio

Katalon Studio is an open-source, comprehensive, and robust test automation tool API, Web app testing, Desktop testing, and Mobile app testing. The key benefit of using Katalon studio is its capacity to combine business levels (API/ Web services) and UI for multiple operating systems like Mac OS, Linux, and Windows. Katalon Studio supports RESTful and SOAP requests with several kinds of commands like DELETE, PUT, POST, with parameterized capacity.

Katalon Studio gives easy deployment by comprising all plugins, and ALM integrations, frameworks in one package. Besides being an open-source solution, Katalon also provides paid support services for enterprises, businesses, and small teams. It is also named as the Gartner Peer Insights Customers’ Choices 2020 for Software Automation Testing. 

Key Features:

• Supports both SOAP and RESTful requests with multiple types of commands like DELETE, PUT, GET, POST, with parameterized ability
• Capacity to combine API and User Interface verification
• Many built-in keywords for creating test cases
• Supports a data-driven method
• Support the most influential assertion libraries, AssertJ for creating fluent assertion with Behavioural Data-Driven style.
• Used for automation tests as well as exploratory tests 
• Suitable for both beginners and experts with the Manual and Scripting modes
• Suitable for non-techies, experts, and beginners with the Scripting and Manual modes 

•    Customizable and Pre-built code templates 

•    Auto-completion, auto-formatting, and code inspection features for the code

Cons

• Does not have support for distributed tests

Official Website: Katalon Studio

2. Postman

It is a collaboration platform for Application Programming Interface development. It is one of the most popular API clients. Postman enables us to plan, build, share, allocate, test, & document APIs. Originally postman was only a Google Chrome plugin. At present, it extends its solution with the native versions of Mac and Window. If in case you do not wish to code then you can select Postman for your API test. 

Postman is one of the best choices for API tests for beginners who do not want to dive under coding in an IDE (integrated development environment) using a similar language as the software developers. Starting from advanced version 7.3 in 2020, this amazing tool assists users in better manage the collections and API elements (monitors, mock server, tests, and documentation) created from API schemas by using the most modern preferences. The current version 7.31.1 for Linux, Windows, and Mac App has been released in Aug 2020 with slight bug fixes.

Key Features:

•    Works on Windows, Mac OS, Linux, and Chrome applications

•    Supports Continuous Integration/Continuous Delivery  service with Newman

•    Simple-to-use REST client 

•    Supports run, test, document, and monitor features

•    The rich interface that makes it simple to use

•    Can be used for both exploratory and automated testing

•    Supports RAML & Swagger formats

•    No requirement to learn a new language

•    Allow users to simply share the information with the team as they can wrap up all the requests and possible responses, and then send it to their teammates

Cons

•    Even though the company version is easy to install and use, it comes with restricted requests

•    Pricing for business is too high

Official Website: Postman

3. SoapUI

SoapUI is the best test automation tool for REST and SOAP APIs. SoapUI acts as a headless functional test tool devoted to API tests. It is an API test tool that is better for complex test scenarios as it lets developers for testing SOAP, REST, and Web Services without any annoyance. It is a headless functional testing tool and gives the user a complete source framework as it is completely committed to API tests. 

The updated version SoapUI 5.6, launched in July 2020, has upgraded 3rd-party libraries (JUnit, commons-logging, org.apache.httpcomponents, and commons-codec) and removed unused 3rd-party libraries (KeenIO, Jackson). To improve testing security, this tool now disables the Load and by default saves project scripts.

Key Features:

• Open-source Package
• Generate tests rapidly and easily with drag-and-drop and point-and-click 
• Enables load testing by test script’s re-usability 
• Creates security scans to execute against all your API testing
• Premium Package
• Supports data-driven tests: Data loaded from Excels, databases, and files. So that they can imitate how client interact with the APIs
• Supports native asynchronous testing as well as CI/CD integrations 
• Assists Endpoint Explorer dialog for customers to send an exploratory request & examine reactions without making a project
• Supports extended HTTP means like PURGE, LOCK, COPY, PROPFIND, UNLOCK.

Cons

• Even though it is simple to execute, the tool lacks documentation

Official Website: SoapUI

4. Tricentis Tosca

Tricentis Tosca is a Continuous tests platform that speeds up tests with a script-less no-code, approach for comprehensive automated testing. If you are searching for a continuous tests platform for DevOps and Agile, this amazing API testing tool has got you covered. Tricentis Tosca can cover a broad variety of apps counting Mobile, Web, Desktop, as well as APIs. This tool is the Gartner leader in Automated Testing.

Key Features:

• Supports the DevOps and Agile Cycle
• Supports a various range of protocols like SOAP, HTTP(s) JMS, Rabbit MQ, REST, TIBCO EMS, AMQP, NET TCP, IBM MQ
• Maximizes maintainability and reuse with model-based automated tests
• API testing can be used across packaged apps, cross-browser, mobile, etc.,
• Enables you to attain sustainable automation testing
• Lessens the regression tests time
• Its interactive test offers test managers to run manual tests and collect results without the requirement to setup Tosca environ
• Supports web service security configuration in the Application Programming Interface Connection Manager
• Users can employ the signature security alternative to sign manifold parts of a message
• QA engineers are allowed to read & write files vigorously with a file connected in the API Engine

Cons

•    The out-of-the-box functionality can be annoying sometimes

Official Website: Tricentis

5. JMeter

It is a free software tool created to perform performance and load tests, yet extensively used for functional API tests. Even though JMeter was purposely introduced for load tests, it is an amazing tool for functional API tests. It comes with myriads of API tests functionalities and additional features to make the procedure more capable. Jmeter works at a protocol layer and supports cross-platform. 

Developers can use this Jmeter as a unit-testing tool for the JDBC database connections testing. Jmeter has plugins based architecture and can generate testing data. It assists Command-line mode, which will be useful for Java-compatible Operating System. The latest release in Nov 2019 is JMeter 5.2. The JMeter 5.2tool has been jam-packed with manifold features and improvements, enhanced user experience, and several bug fixes, like JMESPath extractor, new protocol, HTTP Samplers, StringtoFile, JDBC improvements, and so on.

Key Features:

• Permits you to use several programming languages
• Allows us in replaying the test results
• Supports the team to rapidly create exceptional data (parameter values) for API testing via. CSV files.
• Users can enable the API testing in CI pipelines to thank the integration between Jenkins and this tool 
• Can be used for both dynamic and static resources performance tests 
• Performance and load tests of many varied apps, protocols, and servers
• Support for variable assertions and parameterization and also supports per-thread cookies

Cons

• Encourage heavy loads and visualizes testing reports that waste loads of memory

Official Website: JMeter

6. Rest-Assured

Rest Assured is a free Java domain-specific language that makes testing of the HTTP-based REST service in the Java domain simpler. This open-source tool is designed with the test in mind, and it integrates with any current Java-based automated framework. The REST-Assured API was introduced so that you do not essentially require an HTTP expert. JSON and XML Responses/ Requests are supported by REST-Assured.

REST-Assured offers a BDD (behavior-driven development)-like, a domain-precise language that makes generating API testing in Java easy. It also has loads of baked-in functionalities, which means one does not need to code things from scratch. Starting from REST Assured version 4.0.0, this tool requires at least Java 8, in its place of Java 6 as was formerly required. This version also additional assistance for Apache Johnzon and fixed numerous problems with the initial OSGi support. The current version 4.2.0 intruded in Jan 2020 allowed a great experience for Kotlin developers making use of the spring-mock-mvc module.

Key Features:

• Supports any HTTP method yet has explicit support for several kinds of commands like DELETE, PUT, POST, GET, OPTIONS, HEAD, and PATCH and includes stating and validating e.g. headers, parameters, body, and cookies effortlessly
• Users do not essentially require to code from scratch
• Integrates with the Serenity automated testing framework
• Creates beautiful reports 
• Simply integrated into Continuous Integration/Continuous Delivery tools.
• Supports BDD Then/ When/ Given syntax
• Users do not essentially require to be proficient in HTTP

Cons

• Supports only Java programming language

Official Website: Rest Assured

Wrapping Up

Every enterprise has varied requirements. Finding an ideal tool is still difficult; however, we have the great news that you have now more and more choices than before. Virtually, all of the six API testing tools listed above function well and are ideal options. The best way is to read through the details carefully and choose which better fits your business requirements.