Postman for API Testing — Pros, Cons, and Alternative Solutions

The Significance of API Testing in Software Development

Application Programming Interface or API is no longer an unpopular term in software development. In a three-tier architecture, APIs lay in the domain or business logic tier and ensure the continuity of data transformation between the two other components.

The significance of APIs is reflected in how they help developers save a vast amount of resources when developing applications. With over thousands of public APIs available, developers can access and incorporate almost every shared function into their software without having to start from scratch. 

Additionally, the merge of Agile methodology has stated the vital role of APIs in software development. APIs allow testers and developers to validate the standard functionalities of a product at earlier stages. Hence, Agile teams can meet the requirements for a higher frequency of product releases. 

APIs turn to be the ideal solution for “quality at speed”, and API testing is indispensable to the software development life cycle. Therefore, it is essential for API tests to fulfill all the requirements for functionality, reliability, performance, and security to ensure data connectivity. Regarding the high demand for API tests, testers should utilize the best API testing tools to achieve testing goals. Read more about API testing tips for beginners here.

Postman for API Testing — The Right Tool Yet Not the Absolute Solution

First known as an API validation browser extension, Postman has emerged to be the tool of choice for API development, testing, and managing APIs for QA professionals. Postman was once a side project by Abhinav Asthana that simplified API workflow in software testing and development. By now, the tool has had over 4 million users worldwide. 

Postman can run on multiple operating systems from Windows, Mac OS to Linux. It offers developers more room to develop APIs. For functional testers, Postman allows testers to create tests for API calls without much effort spent on coding scripts. Some of Postman’s outstanding benefits include:

• User-friendliness. With a simple interface, testers can quickly create test suites by filling in templates. Postman also provides code snippets, which support script creation with examples of validations for response time, response code, etc.

• Accessibility. Postman users can access their files seamlessly by logging into their account on a device with the Postman application installed or Postman browser extension.

• Various functionalities. Postman supports all possible HTTP methods, saving progress, converting from APIs to code, changing the API development environment, and many others. 

• Request tracking capabilities. For HTTP Response in Postman, it supports several status codes for users to verify the response. They are Successful requests, Empty response, Bad request, and Unauthorized access, to mention but a few.

These robust features simplify the entire process of building and sharing APIs for developers. When it comes to API testing, especially automation testing, Postman has considerable limitations nonetheless:

• Limited testing area. While Postman is ideal for RESTful API tests, it is not well designed for SOAP APIs and other APIs.

• Low script reusability. Postman users are unable to reuse their pre-written scripts or add more requests. This means testers have to create new test scripts over and over for each project.

• Constrained integration. While APIs enable the Agile process, the tool itself does not support much in integration capabilities. It becomes an obstacle in connecting Postman with the existing systems and collaborating within the team.

Regarding these throwbacks, Postman is highly recommended for manual API testing, specifically for REST APIs. When dealing with advanced and in-depth API tests, an automation tool built for API testing can benefit QA teams in several aspects compared to Postman. One of them is the advantage of well-structured test collections and frameworks. It saves users’ time and effort when it comes to locating and organizing test cases. In Agile teams where every member has to maintain close communication with each other, the nature of Postman turns to be an obstacle for cross-functional collaboration.

We compiled here two potential Postman alternatives in API Testing. The top picks are not exhaustive but balance almost all requirements for a comprehensive API automation testing solution. 

Top Postman Alternatives for API Test Automation

Katalon Studio

Katalon Studio is the complete solution for test automation, including APT automation testing. With its integrated environments, users can generate and validate API calls on web, desktop, and mobile applications. Built on top of Selenium and Appium, it provides users with several needed components, built-in keywords, and test execution templates. 

With Katalon Studio, testers and developers have a unique environment to execute API and Web automation tests. As a solution built specifically for automated test validation, Katalon has comprehensive reporting and tracking tools, giving users the ability to organize and manage tests efficiently. 

Katalon Studio notable features:

• Across-platform testing. With a wide pool of OSs supported, users can perform tests seamlessly across different platforms for API, web, desktop, and mobile testing.

• Native integration. Katalon Studio’s store offers a wide variety of utilities and external integration plugins. They cover almost every need for CI/CD or DevOps practices and team collaboration.

• Rich built-in keyword library. Keywords provided by Katalon Studio are diverse enough for users to perform common test cases. The platform also comes with an Advanced Scripting mode that allows users to customize and deepen their scripts.

• Reporting capabilities. Providing users with powerful tools to export and visualize test results, Katalon Studio helps drive the team’s decision-making process with real-time data and insights.

Price: Free and paid license starting from $69 per month

Website: https://www.katalon.com/api-testing/

SoapUI

SoapUI is an API automation testing tool and a part of the ReadyAPI suite from SmartBear. Initially built for SOAP API testing, it has extended to support REST services. SoapUI is available for multiple platforms, from Windows, Mac OS to Linux.

 There are two versions of SoapUI available for users to experience: SoapUI open source and SoapUI Pro — its paid version. The pro edition has a friendly drag and drop interface that simplifies test execution. Assertion wizard, form editor, and SQL query are other advanced features packed in SoapUI Pro.

SoapUI notable features:

• User-friendly interface allows users to perform API tests using drag and drop, point-and-pick

• A data-driven API automation testing tool with data from files and databases

• Script reusability that allows testers to repurpose pre-written scripts for similar test cases

• Asynchronous API call test services

Price: Free and paid license starting from ___

Website: https://www.soapui.org/

Postman in comparison with Katalon Studio and SoapUI

Key Takeaways

Key factors to be considered when choosing an API automation testing solution

With a functional testing orientation, Postman remains one of the top choices for API validation. The tool is efficient enough to meet the requirements of a decent manual tool for API tests. 

For QA teams with higher demands in API testing, specialized automation tools would be the right solution. Key factors to be considered when choosing an API automation tool include:

• Types of API tests. Accounting for over 95% of all API /Web services, REST and SOAP are the two most dominant API types. An appropriate automation tool should have an extensive pool of supported APIs to meet your current testing needs and further.

• WebUI and Mobile app testing. Besides API testing, the development of multi-platform applications involves Web UI and mobile application tests. Tools that support cross-platform testing natively would have a significant advantage over the rest.

• Test reports. For an automation tool, the capability to generate reports is critical to give QA teams and businesses a robust data-driven approach in making decisions.

You can find out more of Postman alternatives to best fit your testing demands here.