Published: 10 Jun 2019

Why API testing is critical for today’s Business applications?

Last Updated: 08 Jan 2024

In today’s competitive world, businesses should understand the fact that only the best applications thrive well and continue to attract a lot of traffic. This prevalent concept has made software application development and software product development vital for all businesses across industries.

1. API Testing
2. What Does API Testing Revolve Around?
3. How is API Testing Done?
4. How does API Testing Play a Key Role?
5. Top API Testing Tools 2021
6. What are the best practices for API testing?
7. Why Robust API Testing is the Future?
8. How can Testingxperts help you with Effective API Testing?

The Application Program Interface (API) is a set of processes, protocols, routines and tools for building these critical software applications. It is rather an interface that allows software applications to communicate with one another and is mainly used while programming the graphical user interface (GUI) components. There is a lot of significance as an API specifies how its software components should interact with each other.

API Testing

APIs are essential for creating an effective and connected experience for customers and thus businesses are beginning to realize their value. Understanding the depth of its role with respect to applications, hence the importance of API testing has come into place.

This specific testing involves testing of the application interfaces directly as part of the integration testing to determine if the application perfectly meets the expectations for functionality, performance, reliability and security. API testing is one of the challenging test practices in the software and QA process as it reveals the bugs, inconsistencies, and deviations from the expected application behavior.

According to a report on API Testing market outlook from MarketsandMarkets, the global API testing market size is expected to grow from USD 384.3 Million in 2016 to USD 1,099.1 Million by 2022, at a CAGR of 19.69% from 2017 to 2022. It has also been predicted that in the API testing market, the BFSI vertical is expected to grow at the highest rate during the forecast period (2017-2022).

Undoubtedly, investing more time and effort in API testing leads to better quality products that dominate the market with good reliability, security and performance.  

What Does API Testing Revolve Around?

– To ensure the APIs work as expected

– To specify and ensure the application can handle the desired load

– To establish the APIs work seamlessly through the operating systems and devices

– To ensure the data that passes through the API is in lieu of compliance & security

– To make sure all the business rules have been correctly implemented at the API level

– To enable a better user experience

– To ensure easier expansion of applications

– To make sure the API provides the required functionality

How is API Testing Done?

API testing services

1. Set up the Environment:

Initially setting up of the environment should be done with the required parameters that need to be configured for the given API. This includes configuration of server and database as per the API requirement.

2. Define the Test Plan:

The test plan varies based on product type and API. But a solid test plan should cover all scenarios in depth, clearly define the priority of scenarios that need to be tested. It should also include some of the common testing types like unit, integration, security, performance and third-party API tests.

3. Make an API Call:

It is important to make an API call to ensure there are no broken links in the process of testing as it is crucial before proceeding with the actual testing.

4. Combine Data with API Tests:

This step helps to make sure the interface functions as expected with the provided parameters after being configured.

Are these API’s Really Business Critical; How does API Testing Play a Key Role?

The interface is the heart of any application and if the product interface is not good enough, then it shows an adverse effect on its viability. It is a known fact that applications are getting more complex due to the varying end-user needs and in order to meet them, the API’s have become vital tools for businesses across every industry segment. Hence, it necessitates the need for effective API testing at first hand.

Moreover, there is a significant chance that the API’s can be hacked. It is also unfortunate that whenever resources are exposed to the internet, it is likely to be attacked in some way or the other. Hence integration testing and API security testing is critical for all businesses today.

This testing not only ensures security standards but also confirms that the overall system will perform well even under varying loads or network conditions.

Joe Colantonio, an eminent testing domain blogger in his blog on “Why API Testing is Important,”  justifies the importance of API testing, saying that API test process is important with the agile practices on the go and with the internet of things (IoT) all around.

He further adds that agile has increased the frequency with which applications are released which in turn has created an increased demand for new ways to quickly test them. GUI tests are typically too slow to get the test coverage and since API tests do not rely on a User interface(UI) to be ready, thus they can be created early in the software development process.

However, to achieve the best results with API test, it is essential for organizations to follow a set of best practices.

What are the best practices for API testing?


APIs have been the core for applications and should be continuously analyzed as these replicate the complete application performance. So, businesses that underlie on API integrations should continuously follow certain testing strategies to maintain hassle-free data access for the customers and make the application responsive in every aspect.

Make sure to start with API smoke testing: While starting up the API test practice, it is essential to start with the smoke test. The smoke test practice helps to validate the code, ensures to perform several other functionalities such as – it calls the API to verify its response, test the API to check its interactions with other components, etc.

Introduce Exact conditions in the API testing phase: While processing the API testing phase, the development teams need to introduce exact conditions. This way of simulating the exact conditions will ensure that the APIs function correctly and perform the required actions when they are subjected to the work environment.

Track and Save the API responses for Future: While practicing the API testing, the development and testing teams need to track and save the responses obtained from the API test method. When an API undergoes several changes, there are many chances for the API to result in errors. In such scenarios, the already saved responses from the API will help the teams to examine and figure out the reasons which are causing the errors.

Ensure to Perform Negative Testing: In API testing, testing and monitoring the data for a positive response is a constant practice. Along with this, the development teams need to perform negative testing as this method will benefit to validate whether the API is able to respond with an error message or stop with a crash. This will improve the efficiency of the application and help the app to respond in scenarios where invalid data is provided.

Never Ignore Security Tests: The increase in cyberattacks is multiplying the need to secure the applications and the services. Therefore, to secure the applications from exploitation and security breaches, it is essential to adopt testing tools that help to perform and scan security tests along with the additional features.

Top API Testing Tools 2021

Following are the top 6 API tools:

1. Postman:

Postman was initially launched in the market as a Google Chrome plugin. The main aim of Postman is to test API services. Postman is also considered to be a great tool for performing exploratory or manual testing.


  • Users can extract web API data through Postman’s interface
  • It includes collections, workspaces and built-in tools.

2. SoapUI:

Web services REST and SOAP APIs use the platform of SoapUI for carrying out testing activities.


  • The free package of SoapUI gives access to the full source code to the users
  • Drag-and-drop functionality and point-and-click is covered in the free package
  • The fixed package of SoapUI covers data-driven testing, REST, GraphQL, SOAP, JMS and JDBC testing.

3. Apigee:

Apigee is a cross-cloud tool. The features of the Apigee API testing tool can be accessed by users through an editor such as Swagger. API performance can also be measured and tested properly through this tool.


  • Performance-related issues are identified by tracking error rates and response times
  • APIs containing huge amounts of data are compatible with Apigee.

4. Karate DSL:

It has always been difficult to create scenarios for API-based BDD tests. But, with the Karate DSL API testing tool, users can easily undertake this without the need to write down step definitions.


  • It provides a platform where a user can easily write tests
  • As the Karate DSL tool is built on top of Cucumber-JVM, test cases can be easily executed for those projects that use Java language for software development.

5. Rest Assured:

This API testing tool provides a platform where REST services can be easily tested. Rest Assured API testing tool is an open-source tool.


  • It has in-built functionalities through the use of which users need not build code from scratch
  • Several authentication mechanisms are offered by the Rest Assured tool.

6. JMeter:

This API testing tool was developed to perform load testing. As of now, it is well-known for functional API testing. The latest version of JMeter which is “5.4” was rolled out in December 2020 and is capable of additional bug fixes and core enhancements.


  • Users are allowed to include API tests within CI pipelines through the integration of JMeter and Jenkins
  • JMeter tool works really well with CSV files. This tool also helps teams to build unique parameter values for tests.

Undoubtedly Robust API Testing is the Future; But WHY?

It tests the API’s for their capabilities to integrate, stand out to expected functionalities, equally weigh aptly for performance parameters and meet up the security standards

– The robust API testing practice helps to verify code, discover the defects at an early stage and evaluate any unwanted code

– This testing exposes coding issues that either manual or automated tests might miss

– Its superiority is that it is far less time consuming than functional GUI testing

– This aptly tests the core of your product’s functionality and it is the truth that functionality typically determines the end user’s expectations

– With API’s, integration of tools or programs can happen at any point of time to enhance the experience and functionalities of the software

– API test is indispensable and test automation is leveraged currently to make the testing process faster and error-free

API testing challenges

How can Testingxperts help you with Effective API Testing?

Pure play testing services providers like TestingXperts have a good number of expert API testers and provide the perfect environment to test your application interface effectively and efficiently as they have:

– Expertise on a wide range of API protocols like XML, SOAP, JSON, REST, Gdata, YAML, ATOM, RSS, and RDF etc.

– Experience with testing for code level functionality and ensure test accuracy

– Experience to perform end-to-end application validations at various layers of the application

Expertise on leading industry tools for API testing for functional, load, and security testing

– Ample exposure with the automation of API test cases

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